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

Annotations already establish that this is a non-read-only, non-idempotent, non-destructive write. The description adds genuine context beyond them: the composite uniqueness rule on (feature_id, part_id) and the concrete 409 duplicate-failure response, which the agent cannot infer from the schema alone.

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?

Three compact sentences, front-loaded with the core action and immediately followed by the key constraint and the auth requirement. No filler, though it could be tightened slightly by merging the scope note.

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 simple 3-param mutation with no output schema, the definition covers the action, the uniqueness constraint, the failure mode, and the required scope. It omits only minor items such as return shape or typical workflow context, which keeps it just short of fully complete.

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%, so both required IDs and the quantity default are already documented in the schema. The description references the (feature_id, part_id) pair but adds no format, resolution, or defaulting detail beyond what the schema provides, matching the baseline-3 case.

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?

States a specific verb and resource: 'Associate a part with an infrastructure feature.' This clearly separates it from create_part and create_asset_part at a high level, though it never explicitly names those siblings or notes the feature-vs-asset nuance the tool name implies.

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?

Provides useful preconditions (the pair must be unique, duplicates return 409, write scope required), which implies when a call will succeed or fail. However, it offers no guidance on when to use this tool versus the many sibling create_* tools or versus update_infrastructure_asset_part for an existing pair.

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