oeis-mcp-server

Search OEIS Sequences

oeis_search_sequences

Read-onlyIdempotent

Search the OEIS using its query syntax: plain words, "quoted phrases", comma-separated terms, prefixes (keyword:, author:, name:, comment:, formula:, program:, xref:, id:), | for OR, and a leading - to exclude. Returns up to 10 summaries per page. For identifying a sequence from its terms, oeis_identify_sequence is the direct route.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`sort`	No	Result order: relevance (default), number (ascending A-number), created (newest entry first), or modified (most recently edited first).	relevance
`query`	Yes	OEIS query, sent as written. Examples: keyword:core fibonacci; author:Sloane; "Catalan numbers" (a quoted phrase); 1,2,5,14,42 (separate terms with commas: with spaces alone, a negative term after the first starts a new run and fewer than three numbers are not joined). oeis_list_reference topic search_syntax lists the prefixes and operators.
`start`	No	Result offset: 0, 10, … 100 (OEIS shows at most 110 results per query). Pass nextStart from the previous page.

Output Schema

TableJSON Schema

Name	Required	Description
`cap`	No	Page size: 10, fixed by OEIS.
`sort`	No	The result order applied.
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Rows on this page.
`start`	No	The result offset of this page as OEIS served it; below the requested start when that start was past the last result (OEIS then serves the last page).
`notice`	No	Guidance: why nothing matched; that OEIS split the numbers into separate searches, and how to join them with commas into one run; how to narrow the query; or how to reach the next page.
`results`	No	Matching sequences on this page, in the applied order.
`nextStart`	No	Pass as start for the next page; absent on the last reachable page.
`truncated`	No	True when more rows exist than this page shows.
`totalCount`	No	Total rows: the match count OEIS reported, or for outgoing cross-references the number of distinct A-numbers the entry names.
`effectiveQuery`	No	The query as OEIS parsed it (lowercased upstream), e.g. seq:1,2,5,14,42.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 18, 2026

changedInput schema / properties / query / description

Previous value: -"OEIS query, sent as written. Examples: keyword:core fibonacci; author:Sloane; \"Catalan numbers\" (a quoted phrase); 1,2,5,14,42. oeis_list_reference topic search_syntax lists the prefixes and operators."New value: +"OEIS query, sent as written. Examples: keyword:core fibonacci; author:Sloane; \"Catalan numbers\" (a quoted phrase); 1,2,5,14,42 (separate terms with commas: with spaces alone, a negative term after the first starts a new run and fewer than three numbers are not joined). oeis_list_reference topic search_syntax lists the prefixes and operators."

changedOutput schema / properties / notice / description

Previous value: -"Guidance: why nothing matched, how to narrow the query, or how to reach the next page."New value: +"Guidance: why nothing matched; that OEIS split the numbers into separate searches, and how to join them with commas into one run; how to narrow the query; or how to reach the next page."

First observedOct 2, 2026

TDQS

A4.5/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent and openWorld, so the safety profile is covered. The description adds behavioral context beyond them: result volume ("up to 10 summaries per page") and the shape of the query language, which helps an agent predict output. Auth requirements and rate limits are not mentioned.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with the syntax spec and closing with the sibling routing rule. The prefix enumeration is dense but directly actionable; no sentence is filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers query syntax, result volume, and alternative routing, while an output schema exists to carry return-value details and the input schema documents sort/start/pagination. Nothing an agent needs to call this correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description earns extra credit by enumerating the concrete prefixes (keyword:, author:, name:, comment:, formula:, program:, xref:, id:) that the schema defers to an external reference topic, giving the agent usable syntax without a second lookup. It says nothing extra about sort or start.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Search the OEIS using its query syntax") and immediately differentiates itself from oeis_identify_sequence as the identification route. An agent can distinguish this from all siblings without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes term-based identification to oeis_identify_sequence, which is the primary ambiguity for this family. It does not mention the other siblings (oeis_get_sequence, oeis_list_reference) or state when-not to use plain search, so guidance is clear but incomplete.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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