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

Annotations already state readOnly/idempotent/non-destructive, and the description adds meaningful behavioral context beyond that: it works without a key, keyed requests reveal additional role-dependent proposals/deliverables, and decomposition lineage is included. This helps the agent predict auth-dependent behavior and data scope.

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?

The description is dense but compact: it front-loads the primary purpose ('Full listing detail'), then efficiently covers auth variants and extra lineage data. No sentences are wasted, and the structure makes it easy to scan.

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 single-parameter read tool with an output schema and safety annotations, the description is nearly complete. It covers public vs. authenticated behavior and an extra return facet (lineage). It does not mention error cases or explicit alternatives, but those are not critical given the schema and read-only annotations.

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 100% and the only parameter, listing_id, is already described as 'Id of the listing to fetch.' The tool description does not add further parameter-level detail, so it neither improves nor harms the schema's semantic contribution.

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 clearly states a specific verb and resource ('Get one listing' / 'Full listing detail') and adds distinguishing scope: public read fields, key-dependent proposal/deliverable visibility, and decomposition lineage. This separates it from sibling tools like market_browse or market_post_listing without needing to open their schemas.

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?

The description gives clear context for when to use this tool: fetch one listing's full detail, with the important caveat that a key changes what is returned. It does not explicitly name alternatives or exclusions, but the 'one listing' scope and public-read distinction make intended usage obvious.

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