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

Annotations already convey read-only, non-destructive behavior. The description adds useful context that parts are matched against the 'live catalogue', implying a current-data dependency and possibly loose name matching. It does not discuss output shape or error handling, but the safety profile is already covered by 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?

Two sentences with no fluff: the first sentence states the core check purpose, the second provides the only usage guidance needed. The most important information is front-loaded.

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 manually simple 2-parameter read-only tool, the description mostly covers what is needed. The 'live catalogue' note explains matching behavior, and the factors list sets expectations. It would be nice to describe the return value, but without an output schema the absence is not a major 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?

Schema coverage is 100%, so the schema already describes both parts and market. The description adds that part names are free text and matched by the catalogue, which slightly enriches the parts parameter, but it does not clarify the market parameter's effect on compatibility. Overall it is no more than what the schema already conveys.

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 states a specific verb ('check') and a specific resource (PC part compatibility), then lists concrete factors: socket, chipset, RAM type, GPU clearance, cooler height, PSU headroom, connectors. This clearly differentiates it from sibling tools like build_pc or estimate_fps.

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?

It gives a brief usage hint ('Give part names as free text; they are matched against the live catalogue') but never says when to prefer this tool over build_pc or estimate_fps, nor when not to use it. The purpose implies the use case, but no explicit exclusions or alternatives are stated.

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