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

Annotation contradiction: readOnlyHint is false, but the description says 'Read-shaped tools only (anything that buys, sells or writes refuses),' implying this operation is read-only. This is a direct conflict with the annotation. The passthrough comment adds some context, but the contradiction undermines trust.

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 purpose is front-loaded and most sentences add useful context: output fields, use case, passthrough behavior, and read-only policy. The hosting phrasing is slightly convoluted, but the description is not bloated.

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 listing tool with no output schema, the description adequately specifies what the tool returns and why to use it. It could clarify the exact response format, but the listed fields and mapping intent make it complete enough for correct selection and invocation.

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 has zero parameters, so the schema fully covers parameter semantics. The description adds no parameter details, but none are needed; per the rubric, 0 params earns a baseline of 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?

The description opens with a specific verb and resource: 'List every chain Singularity can talk to,' and enumerates the returned fields (family, chain id, native asset, aliases). It also states the mapping use case, clearly distinguishing this list tool from sibling tools like chain_liveness or token_identity.

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 guidance: 'Use this to map a user's informal chain name onto a canonical id.' This tells an agent when to invoke the tool, though it does not name alternative tools or explicitly state when not to use it.

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