Find a free copy

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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), and the description adds real behavioral value beyond them: it prefers PDF over landing page and degrades gracefully ('says so in plain words instead of failing'). It stops short of describing where copies come from or what fields the response carries.

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-loaded with the outcome and preference rule, then inputs and an example. Only the restated input formats duplicate the schema; everything else earns its place.

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?

With one parameter and no output schema, the description covers the essentials an agent needs: what comes back (a link, PDF preferred) and what happens on no-result (plain-words message). A short note on what the plain-words response looks like would close the last gap.

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 100% and the description repeats the accepted identifier formats verbatim from the schema, so it adds little new semantic detail. The example prompt is marginally useful but doesn't explain normalization or error behavior for malformed IDs.

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?

States a specific verb and resource ('Finds a free to read copy of one paper and returns the link') plus a preference rule (PDF over landing page). This clearly separates it from siblings like get_paper (metadata) and search_papers (discovery).

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?

The framing ('free to read copy') plus the example prompt gives an agent a clear trigger condition. It doesn't explicitly name an alternative such as get_paper, so the when-not guidance is implied rather than stated.

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