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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description still adds real behavior: it validates that each id fits the bike, checks for slot collisions, and reports a total at typical prices. That is meaningful beyond the structured metadata, though it does not say whether a failed validation throws an error or returns a diagnostic.

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 tight sentences: purpose first, then input provenance, then validation and return behavior. Nothing is repeated from the schema and no sentence is filler.

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 three-parameter, non-mutating link builder with no output schema, the description covers what it produces (a link), what it returns alongside (a price total), and what it validates. An agent could invoke it correctly from this text alone.

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 the baseline is 3, but the description adds a genuine cross-parameter constraint not in the schema: the part ids must come from the same bike as the 'bike' argument. It also frames part_ids as ordered for display, which reinforces the schema wording.

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 transformation: 'Turn a list of part ids into a link that opens the build on unstocked.bike.' That is a concrete verb plus resource, clearly distinct from the read-only siblings get_build and get_parts, which it explicitly positions as id sources. It stops short of an explicit 'use this instead of X' contrast, so it is not quite a 5.

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?

'Use part ids from get_parts or get_build for the same bike' gives a clear prerequisite and names the two tools that produce valid inputs, which is strong when-to-use guidance. There are no explicit when-not-to-use conditions or failure-path guidance (e.g., what to do if an id belongs to a different bike).

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