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

Annotations already declare readOnlyHint and idempotentHint, so the description adds value by detailing safety (never returns secrets), the attestation chain head inclusion, and the location of the full chain. It clarifies the return structure and explicitly states what it never returns, which is beyond annotations.

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 well-structured with clear sections (purpose, return, usage, location). It's mostly concise, but the phrase 'Never returns any challenge or secret' appears twice, adding slight redundancy. Still, it's efficient and front-loaded with the core purpose.

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?

The tool is simple (one optional param, no output schema), and the description explains the return format explicitly, safety guarantees, and where to find additional attestation chain details. Annotations cover read-only/idempotent hints, so the description is 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?

Schema coverage is 100% and documents manager_id as 'The root to read; defaults to the caller.' The description rephrases this as 'Omit manager_id to read your own,' which adds negligible meaning beyond the schema. Baseline 3 is appropriate since the schema handles parameter explanation adequately.

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 'Read a manager root's bound public key' with specific resource (bound public key) and verb (Read). It distinguishes from sibling tools like federation_key_bind (write) and federation_key_challenge (challenge) by focusing on the read/status aspect.

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 provides usage guidance by explaining the default behavior ('Omit manager_id to read your own') and the context of verification ('A counterparty verifies this root's signatures against it'). It doesn't explicitly exclude alternatives but implies when to use (reading status) without mentioning when not to use.

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