Match yarns to Ravelry

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

Annotations already cover readOnly/idempotent/openWorld, so the bar is lowered. The description still adds useful behavior: results come with a confidence and alternatives, which tells the agent how to handle uncertain matches. It does not mention batching limits or failure behavior, so not a 5.

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, input shape, then return + follow-up. Front-loaded and every sentence earns its place with no repetition of structured fields.

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?

Output schema exists, so return values need not be explained, yet the description briefly and usefully characterizes them (best match, confidence, alternatives). Input, output, and next-step context are all present; only edge behavior (limits, no-match handling) is absent.

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 reported as 0%, so the description must carry the load, and it does: it enumerates the readable fields to supply per item (brand, name, weight, fiber, yards/meters, grams per skein) and clarifies the one-item-per-yarn structure. It omits the enum values for weight and the item cap, which the schema already supplies.

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?

Specific verb+resource: 'Finds the Ravelry yarn behind text read from a ball band, receipt or invoice.' The input-source framing implicitly differentiates it from search_yarns (query-based lookup), though it never names that sibling. Clear purpose, but not explicit sibling routing.

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?

Gives concrete invocation context ('Pass one item per yarn with the raw label plus whatever you could read') and routes the agent downstream ('use the yarn ids with add_to_my_stash or get_yarn_details'). No when-not guidance or ambiguity handling instructions, but the positive guidance is strong.

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