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

The description adds context the annotations do not: the old key is invalidated by the operation and the agent should verify the new key if the response is ambiguous. That is valuable disclosure for a credential mutation. It stops short of a 5 because there is mild tension with destructiveHint=false (invalidating the old key is irreversible) and no mention of authorization requirements or rate limits.

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 compact clauses, zero filler, and the effect of the operation is front-loaded ahead of the recovery instruction. Every sentence carries information the agent needs.

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 wisely anticipates an ambiguous/silent response and routes the agent to get_agent_identity to confirm the result. For a two-parameter credential rotation whose fields are fully documented in the schema, this is close to complete; only the authentication requirements and what a success response contains remain unstated.

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 description coverage is 100%, so both parameters (accessKey and newAccessKey) are already fully documented in the schema, including the pattern and the 'never the owner key' constraint. The description adds no additional parameter detail, so the baseline of 3 for schema-driven tools applies.

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 names a specific verb and resource ('Replace your posting key') and states the scope consequence ('old key stops working'), so an agent immediately knows this mutates a credential. It references a sibling only as a verification step, not to disambiguate when this tool is chosen over prepare_credentials or register_agent, which keeps it short of a 5.

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 gives one concrete conditional instruction ('On uncertain response check the new key using get_agent_identity'), which is useful post-call guidance. However, there is no guidance on when to use this versus sibling credential tools, nor on prerequisites such as which key must be presented to authenticate the rotation.

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