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

With no annotations, the description carries the full burden. It usefully discloses the data source and the completeness policy ('missing figures are omitted; nothing is estimated'), which tells the agent not to expect back-filled data. It says nothing about read-only nature, auth needs, or failure behavior for unmatched lookups.

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 short sentences, front-loaded with the resource and source, followed by invocation and data-quality notes. No filler, no repetition of the name.

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 lookup with no output schema, the description covers source, invocation modes, and missing-data behavior — enough for an agent to call it correctly. It stops short of describing the shape of returned spec figures, which an agent might reasonably want given no output schema exists.

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 0% and no parameters are marked required, so the schema alone gives no guidance. The description compensates well by clarifying the alternative key sets (listing_id OR make+model) and that year is optional — a relationship the bare schema does not express.

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 names the resource precisely (official OEM spec figures) and its backing source (data/spec-cards.json), so an agent knows exactly what comes back. It does not, however, distinguish this from siblings like get_listing, which presumably also returns listing data.

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?

It tells the agent how to call it ('Pass listing_id or make and model, with optional year'), which implies the two supported lookup modes. But it never states when to prefer this tool over get_listing or search_listings, and offers no exclusions or prerequisites.

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