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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the mutation/safety profile is covered. Beyond that the description adds the required permission scope (security.manage) and immutability rules that are not in the annotations. It does not state whether omitted fields are left untouched or cleared, which is a real gap for a partial-update tool.

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?

Three tightly packed sentences with zero filler. The mutable-field list is front-loaded, followed by the immutability constraint and the revoked-policy caveat in descending order of importance.

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 no-output-schema mutation with four fully documented params, the description covers permissions, what cannot change, and the failure precondition (revoked policy). It is close to complete, only missing partial-update semantics and any hint about the response or confirmation.

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% so the schema already documents all four parameters; the description's mapping of 'review deadline' to expires_at and 'expire-when-fixed flag' to expire_when_fix_available is helpful alignment but adds no new syntax or format detail. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

States a specific verb (change/update) plus the exact resource (a disposition policy) and enumerates the mutable fields: reason, review deadline, expire-when-fixed flag. This distinguishes it cleanly from create_security_disposition, revoke_security_disposition, and preview_security_disposition.

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?

Explicitly states what this tool is NOT for: the selector and disposition cannot be changed, and instructs the agent to 'revoke and create instead', routing to the sibling tools. It also gives a hard prerequisite - a revoked policy cannot be edited - so the agent knows when the call will fail.

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