fetch

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

No annotations are provided, so the description must carry the transparency burden. It notes that the tool is 'OpenAI MCP compliant' and reinforces the single-PMID constraint, but does not disclose behavior for invalid PMIDs, rate limits, or the return format beyond 'abstract'. This leaves some ambiguity for unexpected inputs.

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 two sentences, front-loads the core purpose, and includes a pointer to the batch alternative. No wasted words.

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 one-parameter, no-output-schema tool, the description covers purpose and constraint well. It lacks explicit return structure and error handling, but the output is implicitly the abstract. Given the simplicity, it is mostly complete.

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 100% with a detailed description: 'Single PubMed ID (PMID) — NO arrays or comma-separated values.' The description adds the 'exactly one' constraint and batch usage, but the parameter meaning is already fully covered by the schema, so baseline 3 is appropriate.

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 uses a specific verb ('Retrieve') and resource ('abstract for a single PMID'), clearly stating the scope. It distinguishes from siblings by explicitly stating 'Accepts exactly one PMID' and directing multi-PMID requests to fetch_batch.

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 explicitly provides an alternative for a different scenario: 'For multiple PMIDs, use fetch_batch.' This is a clear when-not and alternative. It also implies when to use (when you have a single PMID and need its abstract).

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