library_docs

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

Annotations declare readOnlyHint and openWorldHint, so the description builds on that with valuable behavioral details: caching behavior, version pinning fallback ('wrong/missing tag on GitHub also falls back to latest with a note'), subpages navigation logic, and the fact that output is distilled passages rather than full docs. No contradictions with 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 longer than average but well-structured: a clear opening sentence, a Context7-style comparison, a bullet list of parameters, and notes on version behavior. Every sentence contributes meaning; it is detailed but not wasteful. Slight redundancy ('local and unlimited' vs caching) but overall efficient.

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 the tool's complexity (6 params, output schema present), the description is remarkably complete. It covers parameter semantics, edge cases (version fallback), caching, distillation, and output constraints. An agent has all necessary information to call the tool correctly, including what to expect in the answer.

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 0%, so the description carries the full burden. It explains every parameter: library with examples, query for distillation, max_chars as character budget, refresh for cache bypass, subpages with '0 disables', and version with tag examples and fallback behavior. This fully compensates for the lack of schema descriptions.

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: 'Fetch up-to-date official documentation for a library and distill it under your question.' It clearly identifies the tool's unique function (distillation) and distinguishes it from general web search or URL reading by its focus on library docs and local caching.

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 provides strong usage context: it explains the built-in index, caching benefits ('instant, offline and free'), and the distillation process. It mentions 'Context7-style' as a comparison but does not explicitly name sibling tools or state when NOT to use them. However, the context is clear enough for an agent to infer appropriate usage for library documentation queries.

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