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

Annotations already declare read-only and idempotent hints, and the description adds valuable behavioral context: the credential is HMAC-signed, expires in 10 minutes, contains a hash-chained outcome ledger with specific fields, and can be verified via a separate endpoint. This goes beyond the annotations without contradicting them.

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 dense but purposeful sentences: the first states the action and endpoint, the second explains the credential's internal structure and intended use. No fluff, front-loaded with the core operation.

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 single-parameter GET with no output schema, the description explains the nature of the returned credential, its fields, TTL, and verification path. It does not describe the exact response envelope or error behavior, but it is sufficiently complete for tool selection and basic 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 only parameter, agent_id, is fully described in the schema with a pattern and 'Atlas agent id'. The description does not add extra meaning beyond restating that it is the agent's credential, so it relies on the schema's 100% coverage. Baseline 3 is appropriate.

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 ('Fetch') and identifies the exact resource ('agent's tamper-evident reputation credential') plus the endpoint path. It clearly distinguishes this from sibling tools by naming the unique credential type and its use case in pricing counterparty risk.

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 the tool ('Sellers use this to price counterparty risk before serving a new agent') but does not explicitly mention alternatives or exclusion criteria. This meets the 'clear context, no exclusions' level.

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