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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavior: the personal-API-key auth requirement and the restriction to direct (non-inherited) grants. It does not mention pagination or result caps, which is the only remaining gap for a list endpoint.

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 short sentences, front-loaded with the verb and scope, then the sibling routing, then the auth caveat. Every clause carries information an agent needs to choose or invoke the tool; nothing is redundant.

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 one-parameter read-only list tool with full annotation coverage, this is nearly complete: scope, return shape, sibling routing and auth are all present. Missing pagination/empty-result behavior and the fact that there is no output schema, so the return contract is only described obliquely.

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 the single parameter already documents itself ('The membership id, from list_members'), so the baseline is 3. The description's 'granted directly to one member' reinforces that membership_id is a single-member scope, but adds no format or syntax detail 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?

States a specific verb and resource ('List the permission policies granted directly to one member') and even enumerates what each entry contains (permissions, scope, revision). The word 'directly' carves out a precise scope that separates it from inherited grants, so an agent can identify it without opening the schema.

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 names the alternative ('Grants the member inherits from teams are on list_team_permission_policies') and the condition that selects it (direct vs inherited). It also adds a prerequisite the agent cannot infer elsewhere: 'Requires a personal API key.' Both when-to-use and a hard gating condition are present.

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