ag_capabilities

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

With no annotations present, the description carries the full burden and does well by stating determinism, fixture verification, free guest invocation within rate limits, and the signed provenance envelope in every completion. It does not mention side effects, but this is a read-only listing tool so the absence is acceptable.

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 concise, front-loaded with the primary action and resource, and packs essential details into three sentences. It avoids redundancy and clearly separates what is returned from where to find more comprehensive identity documents.

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 parameterless capability-listing tool, the description is complete: it specifies the output contents, behavioral guarantees, cost constraints, and a pointer to additional identity documentation. No critical information is missing for an agent to decide whether and how to invoke this tool.

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 tool accepts zero parameters, and the input schema is an empty object. Since there are no parameters to document, the baseline of 4 applies; the description appropriately omits parameter details.

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: 'List Agent Guild's invocable utility capabilities' and enumerates the exact content fields returned (id, version, summary, schemas, latency, guest terms). It also distinguishes this from sibling guild_* tools by focusing specifically on ag_* utility capabilities and pointing to identity documents for full 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?

The description gives explicit invocation context: all results are deterministic and fixture-verified, guest use is free within rate limits, and every completion returns a signed provenance envelope. It also directs users to the identity index for full documents, although it does not explicitly contrast with sibling tools beyond the ag_* scope.

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