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

Annotations already declare readOnlyHint and idempotentHint, which are consistent with the 'Read' verb. The description adds value by stating 'Never returns any challenge or secret' and describing the attestation chain head inclusion, providing clarity beyond annotations about what the tool will not do.

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 informative but slightly redundant, as 'Never returns any challenge or secret' appears twice. It also includes a verbose explanation of the attestation chain. While well-structured, it could be tightened without losing clarity.

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?

With no output schema, the description fully covers the return value expectations, including the attestation chain head and the public key fields. It also provides an example and explains the difference from full chain retrieval, making it complete for the tool's simplicity.

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 schema already provides 100% coverage for the single parameter with 'defaults to the caller.' The description reiterates this with 'Omit manager_id to read your own' and gives an example call, but adds minimal new meaning beyond the schema.

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: 'Read a manager root's bound public key' with specific resource and verb. It lists the returned fields and distinguishes from related tools like federation_key_bind and federation_key_challenge by focusing on reading rather than binding or challenging.

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 explains that omitting manager_id reads the caller's own key and mentions that counterparties use it for signature verification. It also points to a well-known URL for the full chain, providing context for when this might be needed. While it doesn't explicitly state when not to use it, the purpose is reasonably clear and distinct from siblings.

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