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

Annotations already signal destructiveHint=true, so the description does not need to restate that. It adds useful semantics by clarifying the upsert behavior: match by email and either add a new member or update the existing member. It does not describe failure modes, permission needs, or role overwrite specifics, but the annotations cover the core safety profile.

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?

The description is two short sentences with no filler. It front-loads the primary action and resource, then provides the allowed role values in a compact list. Every sentence earns its place.

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?

Given a simple 3-parameter tool, full schema documentation, an output schema, and annotations that flag destructiveness, the description is nearly complete. It captures the core upsert semantics and role constraints. The only missing part is explicit usage guidance relative to sibling tools, which is already penalized in usage_guidelines.

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 each parameter already has a description, so baseline is 3. The description adds meaningful extra semantics by stating 'by email', which identifies email as the matching key for the upsert rather than just a field to set. The listed roles duplicate the schema but are still useful.

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 states a specific verb ('Add or update') and resource ('one project member'), and identifies the lookup key ('by email') plus allowed roles. It clearly conveys what the tool does, but it does not explicitly differentiate itself from siblings like upsert_org_member or remove_project_member beyond the resource name.

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?

The description implies when this tool is appropriate—when a caller needs to add or update a single project member by email. However, it provides no explicit guidance about when not to use it, such as when to use remove_project_member or upsert_org_member instead.

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