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

Beyond the read-only and idempotent annotations, the description reveals concrete behavior: it returns the same shape as list_services and provides an error with close matches for unknown IDs. This gives the agent a clear expectation of outcomes without relying solely on annotations.

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 two sentences, covering the action, the parameter source, the return shape, and error behavior. There is no redundancy or fluff, making it efficient and easy to parse.

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 simple get-by-ID operation, the description covers all essential aspects: what it does, how to identify the resource, what the response looks like, and what happens on failure. The lack of an output schema is mitigated by referencing the shape of list_services, making it complete.

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 schema already defines serviceId with constraints and an example. The description adds context by indicating the ID should come from list_services, which clarifies the expected value's origin and format, going beyond the schema's type definition.

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 action (fetch) and resource (a single service) and distinguishes from siblings like list_services by focusing on a specific serviceId. It also notes the return shape matches list_services, further clarifying its purpose.

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 implies usage context by specifying serviceId is 'as returned by code402_list_services', suggesting a typical flow of listing first then fetching. It also mentions error behavior with close matches when the ID is unknown, offering guidance on what to expect. However, it could be more explicit about when to choose this over alternative tools (e.g., list_services or probe_endpoint).

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