io.github.cyanheads/inaturalist-mcp-server

---

Overview

iNaturalist's index of 380M+ georeferenced citizen-science observations of plants, animals, and fungi. Search sightings by area, date, taxon, and annotation; read the community identification thread behind a record; chart when a taxon appears in a place; rank the species of an area; and check what a look-alike is most often confused with. Keyless and read-only, running as a stdio process, a local Streamable HTTP server, or the public hosted endpoint above.

Composes with servers covering institutional specimen records, botanical nomenclature, and geocoding — this one contributes the observation, identification-thread, and phenology layer.

Tools

Tool	Description
inaturalist_list_reference	Decode the controlled vocabularies the other tools filter on — annotation attributes and values, quality grades, licences, ranks, iconic taxa, conservation-status codes
inaturalist_resolve_name	Resolve a common or scientific name to a taxon id, or a place, project, or observer name to its id, as ranked candidates
inaturalist_find_places	Resolve a place name to a place id, or list the places covering a map area, each with its bounding box and containment chain
inaturalist_search_observations	Search georeferenced sightings by area, date, taxon, quality grade, annotation, and conservation status
inaturalist_get_observation	Fetch up to 10 observations by id with their community identification thread and consensus taxon
inaturalist_get_species_counts	Rank the distinct species recorded in an area and period, most-observed first
inaturalist_get_histogram	Build a phenology histogram for a taxon in an area — which months, weeks, or years it is recorded in
inaturalist_get_leaderboard	Rank the most active observers or identifiers for an area, period, and taxon
inaturalist_get_similar_species	List the taxa a taxon is most often misidentified as, ranked by how many times identifiers made the correction
inaturalist_get_taxon	Fetch a taxon profile — taxonomic path, conservation listings by authority, encyclopedia summary, photos, and children

Resources

Resource	Description
inaturalist://taxa/{taxon_id}	Taxon profile by numeric taxon id, as injectable context
inaturalist://observations/{observation_id}	One observation with its identification thread expanded, as injectable context

Both resources mirror data also reachable through inaturalist_get_taxon and inaturalist_get_observation — useful for clients that don't surface MCP resources.

Capability reference

inaturalist_list_reference _tool

• topic selects one table: controlled_terms, quality_grades, licenses, ranks, iconic_taxa, conservation_status_codes; source reports whether it came from iNaturalist or the published spec
• taxon_id applies only to controlled_terms and adds observed_usage — which annotation pairs identifiers have actually recorded for that taxon, with counts
• Every other tool's recovery hint routes here: an unrecognised filter value is not rejected upstream, it silently returns nothing

---

inaturalist_resolve_name _tool

• type: taxon (name-prefix autocomplete) or place / project / user / any (scored cross-kind search); rank narrows taxa only; limit 1–30 (default 10), applied in-process on every type
• Taxon lookup matches a name prefix, not words inside a name — "monarch" hits where "monarch butterfly" misses
• A miss is a result: found: false with guidance naming why, rather than an error
• Each candidate carries kind and id — the identifier every other tool takes. A user candidate also carries login, the value leaderboard entries and an observation's observer relay; its name is the display name

---

inaturalist_find_places _tool

• Exactly one of q (place-name prefix) or all four of nelat, nelng, swlat, swlng; neither or both fails as invalid_geography, as does a box with nelat south of swlat. A blank q reads as unset, and nelng west of swlng is an antimeridian-crossing box, not an error
• q returns places[]; the bounding box returns standard[] and community[] as separate lists
• Each place carries bbox, place_type, admin_level, ancestor_place_ids, location, and slug; boundary polygons are stripped, since one upstream response carries 247 KB of them
• per_page (1–30, default 10) binds the bounding-box arm only, where it bounds standard[] and community[] separately, so cap is per_page × 2. The name-prefix endpoint publishes no page size, and its fixed page is disclosed through the truncation enrichment

---

inaturalist_search_observations _tool

• An area is given in exactly one form — place_id, the lat+lng+radius triple in kilometres (0 < radius ≤ 500), or the four-corner bounding box with nelat at or north of swlat; partial, mixed, a zero radius, or an inverted box fails as invalid_geography
• Filters: taxon_id, d1/d2, quality_grade, captive, term_id+term_value_id, iconic_taxa, hrank/lrank, csi, threatened/native/introduced/endemic, licensed/photo_licensed, and q+search_on
• Ordered pairs are checked before the request: d1 after d2 fails as inverted_date_range (on every tool that takes dates), and an hrank finer than lrank as inverted_rank_range. Equal pairs are valid
• Defaults to quality_grade: ["research"] and captive: false, echoed back as applied_filters on every call
• per_page 1–25 (default 10); page walks the first 10,000 results and cursor continues past it — passing both fails, and a cursor forces an id ordering, which is echoed
• include expands photos, annotations, sounds. identifications and comments are deliberately absent — one thread measures 28 KB, so the thread lives on inaturalist_get_observation

---

inaturalist_get_observation _tool

• 1–10 ids per call, resolved in a single upstream request
• include defaults to ["identifications"]; comments, photos, annotations, and sounds are also available
• Partial success: ids that resolve return in observations, the rest in unresolved; the call fails as not_found only when nothing resolved
• Adds community_taxon and identification_disagreements_count on top of the projected search record

---

inaturalist_get_species_counts _tool

• Distinct species for an area and period, ranked by observation_count — the "what lives here" answer without paging through individual sightings
• Same area forms and filters as the observation search; taxon_id narrows to a clade, such as the birds of a park
• per_page 1–50 (default 25), page for offset — upstream would serve 500 in one page, and the cap is sized by response bytes instead
• truncationCeiling carries the last count shown; the ranking is descending, so nothing left off the page exceeds it

---

inaturalist_get_histogram _tool

• interval: month_of_year (default) and week_of_year fold every year into one seasonal curve; year, month, week, day, and hour bucket absolute dates, to which upstream applies its own default start date
• date_field: observed (default) or created
• taxon_id is optional — omit it to chart every taxon in the area
• Returns every bucket upstream produced in order, zeros included, plus their total — computed across every bucket upstream returned, even past the cap. day/hour over a wide date range can generate thousands of buckets, so the response is capped at 800, kept from the start of the range, with truncated/shown/cap disclosing the cut

---

inaturalist_get_leaderboard _tool

• kind: observers (ranked by observations recorded, carrying species_count) or identifiers (identifications made); count_metric names what count measures
• per_page 1–250 (default 25), page for offset. Both endpoints rank only the top 500, so page × per_page past 500 fails as leaderboard_window_exceeded rather than returning a false zero-hit
• Takes the same area forms, taxon_id, d1/d2, and quality_grade as the observation search

---

inaturalist_get_similar_species _tool

• The taxa a taxon_id is most often corrected from, ranked by misidentification_count — the field-identification check before committing to a look-alike
• An optional area, date range, quality_grade, and captive scope the confusion set to one region; omit them for the global set
• limit 1–50 (default 20), applied in-process — the endpoint publishes no page size and returns its whole set

---

inaturalist_get_taxon _tool

• One taxon_id. Returns kind: "full" with the projected profile, or kind: "outline" listing each section and its byte size when the projection still overflows the budget
• Sections are summary, taxonomy, children, conservation, photos, encyclopedia; name them in sections to fetch a slice, and an unknown name fails as unknown_section
• The upstream record is 95 KB for a common species — per-country checklist membership is dropped, listed_taxa_count kept as a scalar, and ancestors, children, and conservation entries trimmed to their identifying fields
• A named section comes back whole at whatever size, so sum the outline's byte sizes before asking for several

---

inaturalist://taxa/{taxon_id} _resource

• The projected taxon document as application/json, always whole — a resource read has no way to name sections, so use inaturalist_get_taxon when the outline path matters
• taxon_id comes from inaturalist_resolve_name; cached for six hours, matching the service's taxon TTL

---

inaturalist://observations/{observation_id} _resource

• One observation with its identification thread expanded, as application/json
• observation_id comes from inaturalist_search_observations; cached for fifteen minutes, since a thread accrues identifications

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

iNaturalist-specific:

• Keyless, read-only cover of the iNaturalist v1 API — observations, taxa, places, controlled terms, the similar-species graph, and the observer and identifier leaderboards
• Every response is projected in-process. Upstream accepts and ignores its own fields= parameter, so a two-record observation search arrives at 95 KB, a full upstream page of 200 at 4.3 MB, and a common taxon record at 95 KB before anything is trimmed
• Per-endpoint parameter allowlist — an unknown parameter name returns HTTP 200 and the entire global index, so nothing outside the allowlist is ever sent
• In-process rejection of every input upstream would silently widen, narrow to zero, or fail on: a lone lat, an unparseable or impossible d1 such as 2026-02-30, d1 after d2, a term_value_id without its term_id, a zero radius, a box with nelat south of swlat, a page past the result window
• Self-paced outbound traffic with a per-UTC-day request budget, since the API returns no rate-limit headers to react to

Agent-friendly output:

• Applied defaults echoed on every call — quality_grade, captive, and the ordering a cursor forced — so an agent can see the filters that shaped its answer
• Zero-hit notices name the filter most likely responsible and the tool that decodes it, instead of an empty list
• Truncation disclosed unconditionally: truncated, shown, and cap on every path, plus a truncationCeiling where a descending ranking supports one
• Upstream free text — encyclopedia summaries, identification and comment bodies, place guesses, photo attributions — renders inside a markdown blockquote, marking it as third-party content rather than instruction

Licensing and attribution

The API is open; the records are not uniformly open.

• license_code is relayed verbatim and is nullable. A null means all rights reserved — it is never coerced to "", "unknown", or a default licence, and the rendered text spells the null case out in words.
• Photo attribution strings are relayed verbatim, never reformatted or shortened, and must be reproduced wherever the image is. A photo's own license_code is independent of its observation's.
• open is derived from the hosting domain: true for inaturalist-open-data.s3.amazonaws.com, false for anything else, because an unrecognised host is not evidence of an open licence. A licence change moves a photo between hosts, so the flag describes fetch time rather than a permanent property.
• Photos are linked, never proxied. No tool fetches image bytes or emits base64 image content — a URL with its attribution and licence is the whole contract.
• obscured: true marks a locality, not a sighting position. iNaturalist withholds true coordinates for threatened taxa, and the server never sends an Authorization header, so hidden coordinates stay hidden.
• Observer identity collapses to login. The upstream user object carries a real name, an ORCID, and counts; none of it is relayed.

Rate limits and response size

The published terms allow at most 100 requests per minute, ask clients to stay at or below 60, and ask for under 10,000 per day. No rate-limit headers come back, so pacing is entirely self-imposed: outbound requests start at least INATURALIST_MIN_REQUEST_INTERVAL_MS apart (1100 ms ≈ 54 per minute), at most INATURALIST_MAX_CONCURRENT_REQUESTS run in flight, and INATURALIST_DAILY_REQUEST_BUDGET bounds a UTC day. Exhausting the budget is a typed failure rather than a silent degradation.

Controlled terms (24 h), taxon profiles (6 h), places (6 h), the similar-species graph (6 h), and histograms (1 h) are cached in tenant-scoped storage. Observation search, species counts, leaderboards, and observation detail are never cached — freshness is what they are for.

Page-size maxima are sized by measured response bytes across structuredContent and the rendered text together, not by what upstream will serve:

Tool	Bytes per record	per_page max	Default	Upstream would serve
inaturalist_search_observations	~1,970	25	10	200
inaturalist_get_species_counts	~860	50	25	500
inaturalist_get_leaderboard	~140	250	25	500

Each default page fits the 24,000-byte budget a single document gets, and each full page fits 50,000. Nothing is unreachable at the lower caps — page and cursor reach the same records — so the smaller page costs one more call rather than any data.

Known limitations

• Upstream ignores its own fields= partial-response parameter, so every byte is fetched before being projected away. Projection saves the agent's context, not the network.
• total_results is an estimate over a live index. It drifts between calls seconds apart.
• place_type and admin_level have no published code table. The raw integers are relayed and display_name carries the meaning.
• A place crossing the antimeridian has a degenerate bounding box upstream. It is relayed as computed, not repaired.
• Obscured coordinates cannot be resolved, by design. A threatened-taxon record reports a locality with an accuracy radius in the tens of kilometres.
• A section named in inaturalist_get_taxon comes back whole however large it is — truncating a section the caller asked for by name is the failure the outline exists to prevent.
• The daily request counter is per process. A restart resets it, and two processes behind one egress IP do not share it. Every caller of the public hosted instance draws on that one process's budget.
• inaturalist_get_leaderboard can address only the top 500 entries, against the 10,000-result window on observation search.

Getting started

Public Hosted Instance

A public instance is available at https://inaturalist.caseyjhand.com/mcp — no installation required. Point any MCP client at it via Streamable HTTP:

{
  "mcpServers": {
    "inaturalist-mcp-server": {
      "type": "streamable-http",
      "url": "https://inaturalist.caseyjhand.com/mcp"
    }
  }
}

Self-Hosted / Local

Add the following to your MCP client configuration file.

{
  "mcpServers": {
    "inaturalist-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/inaturalist-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "inaturalist-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/inaturalist-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "inaturalist-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/inaturalist-mcp-server:latest"]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.4.0 or higher (or Node.js ≥ 24.0.0).
• No API key required — the iNaturalist v1 API is keyless, and this server never authenticates.
• The published terms ask clients to identify themselves. A descriptive User-Agent with a contact URL is sent by default; keep one in any INATURALIST_USER_AGENT override.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/inaturalist-mcp-server.git

2. Navigate into the directory:

cd inaturalist-mcp-server

3. Install dependencies:

bun install

4. Configure environment (optional):

cp .env.example .env
# edit .env to override defaults — no required vars

Configuration

Variable	Description	Default
MCP_TRANSPORT_TYPE	Transport: stdio or http	stdio
MCP_HTTP_PORT	HTTP server port	3010
MCP_HTTP_ENDPOINT_PATH	HTTP endpoint path where the MCP server is mounted	/mcp
MCP_SESSION_MODE	HTTP session posture: stateless, stateful, or auto. Overrides the stateless declared in src/index.ts.	stateless
MCP_PUBLIC_URL	Public origin override for TLS-terminating reverse-proxy deployments	none
MCP_AUTH_MODE	Authentication: none, jwt, or oauth	none
MCP_LOG_LEVEL	Log level (debug, info, notice, warning, error)	info
MCP_GC_PRESSURE_INTERVAL_MS	Opt-in Bun-only forced-GC pressure loop (ms). Recommended starting point if heap growth is observed: 60000.	0 (disabled)
LOGS_DIR	Directory for log files (Node.js only)	<project-root>/logs
STORAGE_PROVIDER_TYPE	Storage backend: in-memory, filesystem, supabase, cloudflare-kv/r2/d1. Backs the response cache.	in-memory
INATURALIST_USER_AGENT	User-Agent sent on every request to api.inaturalist.org. Keep a contact URL in any override.	inaturalist-mcp-server/<version> (+<repo url>)
INATURALIST_MIN_REQUEST_INTERVAL_MS	Minimum spacing between outbound request starts, in milliseconds.	1100
INATURALIST_MAX_CONCURRENT_REQUESTS	Maximum outbound requests in flight.	4
INATURALIST_DAILY_REQUEST_BUDGET	Outbound requests allowed per UTC day, counted in-process.	9000
OTEL_ENABLED	Enable OpenTelemetry	false

See .env.example for the full list of optional overrides.

Running the server

Local development

• Build and run the production version:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http
  

• Run checks and tests:

  bun run devcheck  # Lint, format, typecheck, security
  bun run test      # Vitest test suite
  bun run lint:mcp  # Validate MCP definitions against spec
  

Docker

docker build -t inaturalist-mcp-server .
docker run --rm -p 3010:3010 inaturalist-mcp-server

The Dockerfile defaults to HTTP transport, stateless session mode, and logs to /var/log/inaturalist-mcp-server. OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Directory	Purpose
src/index.ts	createApp() entry point — registers tools and resources, inits the service.
src/config	Server-specific environment variable parsing and validation with Zod.
src/mcp-server/tools	Tool definitions (*.tool.ts) plus the shared filter, record, and taxon-document helpers.
src/mcp-server/resources	Resource definitions (*.resource.ts) — taxon and observation.
src/services/inaturalist	iNaturalist service layer — allowlisted client, pacer, cache, and response projections.
tests/	Unit and integration tests mirroring the src/ structure.

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic
• Use ctx.log for logging, ctx.state for storage
• Register new tools and resources in the createApp() arrays
• Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.