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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds value by stating it only reads an existing event and never resends it, which clarifies the non-mutating and non-sending behavior beyond the annotations. It doesn't describe the return format, but the output schema exists, so the description doesn't need to. This is a solid 4.

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 with zero waste. It front-loads the primary use case and immediately clarifies the non-resending behavior. Every word earns its place.

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?

Given the tool's simplicity (one parameter, clear annotations, and an output schema), the description is complete enough for an agent to call it correctly. It covers the purpose, the read-only nature, and the non-resending behavior. The only minor gap is not explicitly stating what the output contains, but the output schema handles that. A 4 is appropriate.

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%, so the schema already documents the 'id' parameter with a pattern and length constraints. The description doesn't add additional parameter semantics beyond what the schema provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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 purpose: to verify an existing durable public Sup receipt. It specifies the verb 'verify' and the resource 'Sup receipt', and distinguishes it from siblings by emphasizing it only reads an existing event and never resends it. This is specific and unambiguous.

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 context on when to use this tool: when the user asks to verify an existing durable public Sup receipt. It also explicitly states what it does not do ('never resends it'), which helps differentiate from potential alternatives. However, it does not explicitly name alternative tools or conditions for when not to use it, so it falls short of a 5.

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