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

Annotations already mark this destructive/non-idempotent, and the description adds substantial context beyond them: it sends real messages one per seed and step, test mode does NOT redirect seed inboxes, and it requires an approval_token round-trip with a documented {error:"approval_required", approval_token, summary} response. The guardrail statement clarifies scope of side effects.

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 action, then prerequisites, then the next-step tool, then the approval flow. Information density is high and every sentence contributes, though the run-on phrasing makes it longer than strictly necessary.

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 zero-required-param, no-output-schema mutation tool, the description covers side effects, prerequisites, follow-up tooling, the guard/approval flow, and even the error return shape. An agent has everything needed to call it and interpret a refusal.

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 both parameters are documented in the schema, so the baseline is 3. The description goes further by explaining the approval_token lifecycle (returned on the guarded response, then passed back on the retry), which is behavioral context the schema's one-line description does not convey.

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?

Starts with a specific verb and resource: send the template under test (rendered step 1 and step 2) from the project's mailbox to every seed inbox, one message per seed and step. This is unambiguous and clearly separable from the sibling refresh_inbox_test_results, which it names as the read-side counterpart.

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?

States when to use it (now, to test the template against seeds) and explicitly routes the agent to refresh_inbox_test_results 'a few minutes later' for results. It also lists the refusal preconditions (no seeds, no read-access mailbox, From failing live check, invalid content), which is exactly the when-not guidance an agent needs.

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