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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description does add one genuine behavioral fact beyond the annotations: result ordering ('OEM parts first, then verified alternatives'). It says nothing about auth needs, rate limits, or result breadth.

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?

Purpose is front-loaded in the first clause, followed by a compact colon-led example list. The enumeration is longer than strictly necessary but remains scannable and informative rather than padded.

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?

An output schema exists, so return values need not be described, and the read-only annotations carry the safety profile. Combined with 100% schema coverage, the description supplies enough context to call the tool correctly, though it could note its relationship to the compatibility-checking siblings.

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 description coverage is 100% and both parameters are already documented with rich examples in the schema itself. The description's example list largely mirrors the 'model' and 'part_type' schema descriptions, so it adds little parameter meaning beyond structured data. Baseline 3 applies when the schema does the heavy lifting.

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 question ('Which parts and accessories fit this model?') and enumerates concrete resource examples (water filters, cartridges, lenses, RAM, SSDs) that make the discovery intent unambiguous. It does not, however, name or contrast against close siblings like check_fit, check_compatibility, or identify_product, so differentiation must be inferred.

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 example device/part pairings, which show the tool's scope, but there is no explicit when-to-use, when-not-to-use, or alternative tool named. An agent can guess it is a discovery tool, but nothing tells it to prefer check_compatibility for a specific known pair.

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