Ferritin — Rust documentation

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

The annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior, so the description is consistent. However, it adds no additional behavioral context such as error handling, return format, or interaction with external crates beyond what annotations already convey.

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 a single accurate sentence with no filler. Every word contributes to explaining the tool's core function.

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 single-parameter, read-only lookup tool with rich parameter schema and annotations, the description is sufficient. The absence of an output schema is not a gap because the purpose ('Show documentation') makes the return type obvious.

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?

The schema description covers the 'path' parameter completely (100% coverage) with examples and semantics for version requirements. The tool description adds no extra meaning beyond restating that the path points to a Rust item, so the baseline of 3 applies.

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 ('Show documentation') and identifies the resource ('Rust item') and the key qualifier ('by path'). This clearly differentiates the tool from the sibling 'search', which is likely for finding items rather than direct retrieval.

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 implies usage when you know an item's path, but it does not explicitly mention the sibling 'search' tool as an alternative for cases where the path is unknown. There is no explicit when-to-use versus when-not-to-use guidance.

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

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

Annotations establish the tool as read-only, idempotent, and non-destructive. The parameter description adds valuable behavioral nuance beyond these annotations, explaining that without a crate the search runs over a 'much shallower dataset' and 'cannot see any crate's actual documentation.'

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 one-sentence description is extremely compact and front-loaded with the verb 'Search.' It efficiently communicates both usage modes with no wasted words or repetition of schema information.

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?

The definition is largely complete: annotations cover safety, the schema thoroughly explains parameter behavior, and the description clarifies the dual-mode nature. However, there is no output schema and the description does not state return format or pagination, which is a minor gap for a search tool.

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 parameter descriptions are exceptionally detailed, including version syntax, examples, and mode-dependent behavior. The main description also contributes semantic meaning by indicating that `crate` is optional and changes the search target.

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 verb 'Search' and distinguishes two resources: items within a crate's documentation, or crates themselves when no crate is given. It effectively differentiates this search tool from the sibling 'get' tool by emphasizing discovery across documentation.

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 input schema provides explicit usage guidance: 'Omit only to discover which crate to use' and 'If you already know the crate name, always pass it.' This gives clear decision criteria for when to use each mode, though alternatives like the sibling 'get' tool are not mentioned.

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