fetch_npm_docs

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

With no annotations provided, the description carries the full burden and does well by disclosing key behavioral traits: it automatically extracts relevant sections (Installation, Usage, Examples, API), prioritizes useful content, returns Markdown format, and handles truncation via max_bytes. However, it doesn't mention rate limits, error handling, or authentication needs, leaving some gaps for a tool with no annotations.

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 with clear sections (purpose, usage guidelines, best for, not suitable for, args, returns, example) and front-loaded key information. It's appropriately sized but has minor verbosity in comparisons (e.g., 'Better than using curl or WebFetch because it:'), which slightly reduces efficiency.

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?

Given no annotations and no output schema, the description does a good job covering purpose, usage, parameters, and return format (JSON with content, size, truncation status, version). However, it lacks details on error cases, response structure, or potential limitations like network dependencies, which would enhance completeness for a tool with such sparse structured data.

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. It explains both parameters: 'package' as npm package name with examples (e.g., 'express'), and 'max_bytes' as maximum content size with default 20KB and note to increase for large packages. This adds meaningful context beyond the bare schema, though it could specify units or constraints more precisely.

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 clearly states the tool fetches npm package documentation from registry READMEs, specifying the exact resource (npm package documentation) and action (fetching from README). It distinguishes from siblings like 'npm_metadata' (which likely provides metadata) and 'fetch_pypi_docs' (for Python packages), making the purpose specific and differentiated.

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 includes 'USE THIS WHEN' for installation instructions, usage examples, API reference, or quickstart guides, and 'NOT SUITABLE FOR' external documentation sites (directing to docs_url from npm_metadata + WebFetch). It also compares to alternatives like curl or WebFetch, providing clear context on when to use this tool versus others.

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