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

readOnlyHint=true already tells the agent this is a safe read, but the description adds real value beyond the annotation: it discloses the composition of the result (humans plus pending invites plus service principals 'marked as such'), which prevents misreading service tokens as human users. It does not address pagination or result size, so not a 5.

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?

Front-loaded with the core answer ('who has access'), then the detail, then usage. Dense but every clause carries information. Minor drag from the multi-level parentheticals ('the twin of ...', 'the board agent, service tokens'), which are illustrative rather than load-bearing.

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 input params and no output schema, the description carries the full disclosure burden and does so by describing the return shape field-by-field. Nothing an agent needs to call this correctly and interpret the response is missing.

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 tool takes zero parameters, so there is nothing for the description to clarify and no schema gap to compensate for. The description correctly avoids inventing filtering options that do not exist.

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+resource (who has access to the organisation) and enumerates exactly what comes back: member email, status, role, current-user flag, pending invites, and Ankra service principals. This scope is distinguishable from the neighbouring list_organisation_roles and list_organisation_variables tools without opening any 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 use cases ('access reviews', 'who is the admin here') and the exclusions: membership changes are not here but in 'portal or CLI lanes'. It also identifies the CLI equivalent it mirrors. An agent knows both when to call it and when not to.

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