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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the description doesn't need to restate those. It adds useful contextual value by disclosing that the response includes the purchase link, which is not evident from the schema or 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?

A single, front-loaded sentence that states the action, target, and key detail about the return value. Every element earns its place and there is no fluff.

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 single-parameter read operation with strong annotations, the description is complete: it tells the agent what action to take, which parameter to provide, and what notable data to expect. The sibling tools help situate it, and no critical invocation information is missing.

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?

With 0% schema description coverage, the description compensates by explaining that 'id' is the plan identifier and provides a concrete example ('R2G-7224'), which gives format insight beyond the plain string type. It could further explain how to obtain the ID, but the example is sufficient.

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 uses a specific verb ('Get') with a clear resource ('one plan by its id'), and distinguishes itself from siblings by indicating a singular ID-based lookup rather than listing destinations or searching plans. The example ID format ('R2G-7224') reinforces what is being fetched.

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 phrase 'by its id' clearly implies this tool is for cases where the plan ID is already known, which contrasts with search_plans for finding plans. It does not explicitly name the alternatives or provide when-not-to-use guidance, but the context is unambiguous enough for an agent.

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