download_pdfs

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

With no annotations present, the description carries the full burden and does a solid job: it discloses the 50-item cap, that paywalled content is skipped and never bypassed, the naming convention, folder resolution rules including the default, and that files are validated by the %PDF magic bytes with HTML login/bot-check pages rejected and reported as failures. It does not state rate limits or authentication requirements, which keeps it from a 5.

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 core action and its limits, and the second paragraph is dense with operational detail rather than filler. The mid-paragraph 'folder:' label is slightly awkward but the text is otherwise tight and every sentence 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?

For a two-parameter tool with no annotations and no output schema, the description covers the critical unknowns: which papers are downloadable, where files land, how they are named, and how unverifiable files surface as failures. Missing return-value structure (e.g., counts or per-PMID status list) is a minor 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 description coverage is 0%, so the description must compensate, and it does so well for 'folder': absolute path vs. a sub-folder name resolved under PUBMED_PDF_DIR with a stated default of ~/pubmed_pdfs. For 'pmids' it adds only the max-50 constraint and the PMID<id>.pdf output mapping, leaving the expected ID format implicit.

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 ('Download open-access PDFs for the given PMIDs') plus the output artifact ('as PMID<id>.pdf'), which clearly separates it from abstract/fetch siblings like fetch_abstracts and pubmed_fetch. It stops short of naming an alternative tool explicitly, so it lands at 4 rather than 5.

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 description conveys scope constraints that imply usage (open-access only, max 50 PMIDs, paywalled papers skipped rather than bypassed), which tells the agent this is not a general access tool. However, it never states when to prefer this over check_access or search_with_access, nor any prerequisite step for obtaining PMIDs, so guidance remains implicit.

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