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

With no annotations, the description carries the burden and does well: it discloses that the call is free, requires no wallet/payment, returns a fixed sample rather than computing on input, and mirrors the paid-call envelope. It omits whether the sandbox counts against quotas or is rate-limited, which would complete the picture.

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 key fact ('Free, and no wallet needed') and four short sentences that each carry information. Slight redundancy in 'that is what makes it free', which restates the fixed-sample idea rather than adding a new constraint.

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 two-required-enum-param tool with no output schema, the description supplies the critical missing piece: what a return value looks like (same envelope/field names/deliverable shape as a paid call). What's left unexplained is the relationship between the 16 modes and the sample returned, a minor gap.

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 100% and both params are enums with descriptions, so the schema already documents mode and agent fully. The description only re-touches 'for a mode' and says nothing about how the coach (agent) choice affects the sample, so it adds no meaning beyond the schema.

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: it returns a schema-valid sample response for a given mode/coach, with the same envelope and field names as a paid call. The contrast with a real 'paid call' implicitly separates it from call_coach/call_action/call_tool, so an agent can tell it apart without opening siblings' 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?

Explicitly directs the agent to use it before a real call ('Build your integration against this first') and clarifies that it is not an answer to input, implying the paid siblings are for actual work. It stops short of naming the alternatives explicitly or stating hard exclusions (e.g., don't use for production data).

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