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

Annotations only declare the mutation/idempotency profile; the description adds substantial non-obvious behavior: upfront worst-case hold with refund of the unused part, a hard stop at max_lookups, 7-day result retention, a 2-concurrent-run cap, and a named error list including quota_exhausted with the hold needed. Nothing here contradicts readOnlyHint=false / destructiveHint=false.

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?

Front-loaded with the core purpose and per-kind semantics before cost and error detail, and nearly every sentence carries operational information. It is a dense single paragraph with cost/error detail packed into long clauses, which slightly hurts scanability.

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 an 8-parameter async job tool with nested objects and no output schema, the description supplies the return shape (id like run_..., status queued, estimated_max_lookups, lookups_held, status_url, results_url), the cost model per kind, retention, and the failure modes — everything needed to call it and interpret the result.

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%, so the baseline is 3; the description still adds value by tying parameters together (which params each kind needs, max_lookups doubling as the hold, max_pages walking limit of a parcel_search body). Minor gap: it doesn't restate the fields/preset interaction beyond what the schema already says.

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 ('Submit work ... as an asynchronous run') plus the immediate effect ('returns a run id at once') and the delegation to get_run for progress/results. It then enumerates the three kind values with distinct semantics, so an agent can tell start_run apart from the synchronous fetch_batch, parcel_enrich and parcel_search siblings.

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?

Explicit routing rules: use this when work is 'too large for one call', otherwise fetch_batch is the synchronous form, with concrete thresholds (2000 locations vs 10/100 batch size; 1000 enrich items; max_pages 1-40). Each kind names the sibling it mirrors, so the when-to-use decision is fully specified rather than inferred.

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