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

With no annotations, the description carries the behavioral burden. It implicitly conveys a read-only metadata lookup by listing stable version, downloads, and license, and the output schema covers return values. However, it does not mention error behavior for unknown packages, rate limits, or whether data is cached.

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?

Two sentences, front-loaded with the returned fields and ending with a usage cue. No filler text; the field list is dense but useful for selection.

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 tool is simple (one required string parameter) and has an output schema, so return values need no further explanation. The description covers what is fetched and a primary use case, making it sufficient for correct invocation, though a note on package-name format would close the remaining 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?

The single parameter 'package' is not documented in the schema (0% coverage) and the description does not specify its expected format (e.g., exact crate name like 'serde'). The context implies it is the crate to look up, but that is the minimum viable interpretation rather than added clarity.

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 identifies the resource (a Rust crate on crates.io) and enumerates the fields it returns, so an agent knows it retrieves crate metadata. It does not explicitly contrast itself with sibling tools like npm_package or pypi_package, though the 'Rust crate' framing implicitly differentiates it.

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 sentence 'Use to choose or audit a Rust dependency' provides a clear, if narrow, usage context. It names no alternatives or exclusions, leaving the agent to infer when another tool (e.g., package_vulnerabilities) would be more appropriate.

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