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

Annotations only say readOnlyHint=true; the description goes well beyond by disclosing async polling semantics, the two possible return states (finished plan vs. current progress), expiry behavior, and the recovery action when the job no longer exists. That is exactly the operational context an agent needs for a polling tool.

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 short sentences, front-loaded with the purpose and the prerequisite, then the two outcomes, then the expiry fallback. No wasted clauses and nothing buried.

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?

No output schema exists, and the description compensates by describing what is returned (finished plan or progress). Combined with the polling lifecycle and expiry guidance, an agent has everything needed to call and interpret this tool correctly.

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?

There is a single parameter with 100% schema description coverage, which already says 'The jobId returned by build_plan.' The description reinforces the same origin but adds no new syntax, format, or constraint details beyond the schema. Baseline 3 for a fully documented single param.

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 ('Check on a shopping plan') and immediately scopes it to plans that build_plan reported as still building. It names the sibling build_plan and the exact handle (jobId) that routes an agent here rather than to any other tool.

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 explicit when-to-use ('plans build_plan reported as still building'), what you get back in each case, and an explicit fallback ('if the job is gone, just call build_plan again'). That is the alternative plus the condition that selects it.

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