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

With no annotations, the description carries the full behavioral burden not only for safety but also for side effects. It clearly discloses that no payment is settled and no usage is recorded, while noting that the provider's real response is returned. This gives agents essential information for safe and correct invocation.

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 compact, starts with the primary behavior, then quickly moves to validation and consequences, and closes with the intended use cases. No filler or redundancy.

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-parameter tool with no output schema, this description covers the tool’s purpose, side effects, validation behavior, and appropriate contexts. Nothing critical is missing for an agent to decide whether and how to call it.

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?

The input schema already documents both parameters (service and input) with 100% coverage enabled. The description adds the semantic nuance that the input is validated against the service's schema reliable, which is useful but not extensive, keeping this at baseline.

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 the tool runs a service without payment, distinct from the paid calling flow. It names the resource (a service), the verb (run), and specifies the free/demo nature, making it easily distinguishable from call_service.

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 explicitly states when to use this tool: for demos and checking output shape before committing to a paid call. It implies when not to use it (any final/paid operation), though it does not directly name call_service as the alternative.

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