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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds behavioral context by describing the output as a side-by-side comparison matrix and listing the specific axes of comparison (creator, layer, agent delegation, etc.), which goes beyond what annotations alone provide. It could detail the return structure further, but for a 0-parameter tool with a fixed protocol set, this is sufficient.

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, front-loaded with the core purpose and immediately followed by usage guidance and an alternative. Every sentence earns its place with no redundancy.

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 (no params, no output schema) and the solid annotations, the description fully covers what the tool does, when to use it, and how it differs from the sibling. The inclusion of example queries and the explicit alternative makes it complete for an agent to invoke correctly.

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?

There are zero parameters, so the baseline is 4. The description correctly omits parameter details because none exist; the input schema fully covers this (vacuously). No additional parameter semantics are needed.

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 a side-by-side comparison matrix') and precisely identifies the resource (all five agent payment protocols) and the comparison dimensions (creator, layer, agent delegation, etc.). It also distinguishes itself from the sibling tool get_protocol_info by noting it's for the full landscape rather than single-protocol details.

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?

It explicitly states when to use the tool, with concrete example queries ('AP2 vs ACP', 'which protocol handles budgets?', etc.), and provides a clear exclusion: use get_protocol_info for deep details on a single protocol. This leaves no ambiguity about tool selection.

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