get_open_access_pdf

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

With no annotations provided, the description discloses key behavior: it returns the best OA copy plus alternatives, and sets is_open_access false when no free version is known. This goes beyond a generic 'find' statement, though it could mention more about potential errors or output format.

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?

The description is well-structured and concise: purpose, usage, and argument definition in three tight sections. Every sentence earns its place with no filler.

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?

For a single-parameter tool with an output schema, the description sufficiently covers the workflow and return behavior. It explains what the tool does, when to use it, and what to expect in the response.

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?

The only parameter, doi, is described in detail with a concrete example, fully compensating for the absent schema description (0% coverage). This adds real meaning beyond the schema's bare type declaration.

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?

The description opens with a specific verb and resource: 'Find a legal open-access PDF for a DOI via Unpaywall.' This clearly distinguishes it from sibling search/get tools for other databases.

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?

It explicitly advises 'Use this after CrossRef/OpenAlex/ERIC turns up a paper you want to read in full,' giving a clear when-to-use context. It does not name alternatives or exclusions, but the tool is unique among siblings for OA PDF retrieval.

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