check_access

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

With no annotations present the description carries the full burden, and it delivers: it discloses the credential requirement (UNPAYWALL_EMAIL or NCBI_EMAIL) and the degraded behavior without it (only PubMed Central links found), plus the 100-PMID ceiling. The semantic caveat about false negatives is exactly the kind of context an agent cannot infer from structured fields.

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

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

Front-loads the classification outcome, then layers in mechanism, caveat, limit and prerequisite in four tight sentences. No filler and no repetition of the tool name.

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

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

There is no output schema, so the description appropriately defines the return categories itself, along with the lookup mechanisms and environment prerequisites. An agent has everything needed to call it correctly and interpret results.

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

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

Schema coverage is 0% for the single pmids parameter, so the description must compensate; it contributes the hard constraint of max 100 PMIDs per call, which the schema does not express. It stops short of specifying the PMID format (string vs numeric), leaving a minor gap.

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

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

Uses a precise verb ('Classify each PMID') and enumerates the exact output taxonomy — open-access PDF, landing page only, no open access found, unchecked — so the tool's function is unmistakable. This clearly separates it from siblings like download_pdfs and pubmed_fetch, which retrieve rather than classify access status.

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

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

Explains the meaning and limits of the result ('no_open_access_found' is not proof of inaccessibility) and states the operational cap of 100 PMIDs per call. It does not explicitly name when to prefer this over siblings such as search_with_access, but the usage context is clear.

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