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

The annotations already declare readOnlyHint=true, indicating a safe read operation. The description adds contextual value by informing the agent that input comes from the payment link or confirmation, but does not describe the return format or any further behavioral details. Given the annotation coverage, a score of 3 is appropriate.

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 a single, front-loaded sentence that immediately conveys the tool's purpose and input requirements. Every word earns its place, with no unnecessary repetition or filler.

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, read-only tracking tool with two fully documented parameters and no output schema, the description sufficiently covers the purpose and inputs. It could be slightly more explicit about what the response contains, but the question format ('Hoe ver is een verstuurde brief?') implies a status answer. Overall, it is adequately 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 input schema provides complete descriptions for both parameters (sessie and referentie), and the tool description essentially repeats the same information without adding new meaning. With 100% schema coverage, the baseline of 3 applies.

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's function: tracking the progress of a sent letter ('Hoe ver is een verstuurde brief?'). It also specifies the required input (session ID or reference), making the purpose unambiguous and distinct from sibling tools like bestellen, document, landen, and prijs.

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 provides clear usage context: use this tool when you need to know the status of a shipped letter. It explicitly tells the agent what information to provide (session ID or reference), but does not explicitly mention when not to use it or name alternative tools. This corresponds to 'clear context, no exclusions'.

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