add_project_member

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

Annotations supply only destructiveHint=false, so the description carries most of the burden and does so candidly: it discloses that the tool is untested and that the identity field is sent under a guessed key, which is the single most decision-relevant fact here. It still omits permission prerequisites, behavior when the member already exists, and error semantics, which keeps it from 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?

Two tight sentences with the experimental warning front-loaded ahead of the technical caveat, so an agent sees the risk first. No filler or repetition, though the telegraphic style leans on the reader knowing REST conventions.

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 three-parameter mutation with no output schema and near-empty annotations, the description covers the reliability risk but not the operational surface: required privileges, idempotency, and what a successful call returns or confirms. Adequate to attempt the call, insufficient to predict its outcome.

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 0%, so the description must compensate, and it does clarify the least obvious parameter by spelling out that `identity` accepts an IAM id, username, or service id and is forwarded verbatim. The `role` enum and `project_id` are left entirely to the schema, so coverage of the parameter set is partial.

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 identifies the operation only indirectly, by naming the wrapped endpoint (POST /v2/projects/{id}/members), which an agent must decode into 'add a member to a project'. It never states in plain terms that it grants a role to an identity, and it does not differentiate itself from the close siblings update_project_member, remove_project_member, or list_project_members.

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?

There is no guidance on when to call this versus update_project_member (changing a role) or list_project_members (checking existing membership). The only conditional information is the 'EXPERIMENTAL — untested' warning, which is a reliability caveat rather than usage direction.

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