Add testers to a project

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

No annotations are provided, so the description carries the full behavioral burden. It says it 'creates tester resources' but does not disclose idempotency (what happens if an email already exists), whether invitations are sent, required permissions, or any limits (schema caps emails at 999). For a mutation tool with zero annotation coverage this is a significant gap.

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?

A single front-loaded sentence that states the action and the key scoping distinction with no filler. It is efficient, though terse enough that it omits useful behavioral and parameter detail.

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 annotations, no output schema, and 0% parameter description coverage, the description would need to explain mutation behavior, the projectId parameter, and limits. It covers only the action and scope, leaving the agent under-informed for correct invocation.

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. It only references 'the given emails' and never explains the projectId parameter, email format/validation, the 999-item cap, or that projectId is optional (defaulting to context). It adds little beyond the raw 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 (creates tester resources), the resource (testers), and the scope (project level, not tied to a group). The parenthetical explicitly distinguishes it from the group-scoped sibling firebase_appdistribution_add_testers_to_group, so an agent can route correctly 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?

The phrase 'at the project level (not tied to a group)' implies when to pick this over the group variant, which is useful routing context. However, it never names the alternative tool or states exclusions/prerequisites (e.g. when to use add_testers_to_group instead), leaving the agent to infer the decision.

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