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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety profile is covered. Description adds context about output fields (creator, maturity, repo URL, layer) but no additional behavioral traits beyond what annotations provide. No contradictions. Score is 3 per rubric: annotations cover safety, description adds some context.

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?

Two sentences, front-loaded with the main purpose and return fields, followed by usage guidance and alternative. Every sentence earns its place; no waste.

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 (1 param with full schema coverage, no output schema, annotations covering safety), the description is complete: it explains what the tool returns, when to use it, and when to use the sibling. No gaps.

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% for the single parameter 'protocol' with enum and clear description. The tool description adds value by providing examples and associating each protocol with its layer (e.g., 'ap2' for Google's authorization layer). This goes beyond the schema, so score 4.

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?

Description clearly states 'Get the canonical description of an agent payment protocol including creator, maturity level, repo URL, and what layer it operates at'. It specifies the resource (protocol info) and the fields returned. It distinguishes from sibling compare_protocols by noting when to use each.

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?

Explicitly states when to use ('when the user asks about a specific protocol') with concrete examples, and when not to use ('Use compare_protocols instead when comparing multiple protocols'). Clear alternative provided.

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