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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds meaningful behavioral context beyond those flags: it discloses that part names are given as free text and matched against the live catalogue, and enumerates the specific checks performed. This tells the agent how input is handled and what the tool actually evaluates.

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, zero filler. The first sentence front-loads the purpose and enumerates what is checked; the second covers the input format and matching behavior. Every clause earns its place.

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 read-only check tool with two parameters and no output schema, the description covers purpose, input format, and behavior thoroughly. The only notable gap is that it does not describe the return format (e.g., a conflict list or pass/fail summary), which matters given no output schema exists to carry that information.

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 baseline is 3, but the description adds real value on top: it clarifies that parts should be supplied as free-text names that get matched against a live catalogue, which informs how the agent should formulate the parts array (natural names, not catalogue IDs). The market parameter is fully covered by the schema enum and description.

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 resource ('a set of PC parts') and enumerates the exact compatibility dimensions covered (socket, chipset, RAM type, GPU clearance, cooler height, PSU headroom, connectors). This clearly distinguishes it from siblings build_pc and estimate_fps, which concern configuration and performance respectively.

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?

Usage is implied through the clear purpose statement – an agent facing a compatibility question would infer this tool is the right one. However, the description never explicitly mentions when not to use it or points to alternatives like build_pc or estimate_fps for adjacent needs, leaving the routing entirely to inference.

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