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

With no annotations, the description carries the burden and does well: it discloses the blocking wait, the destructive side effect ('the code is consumed'), and an audit trail ('the release is logged'). It does not say what happens on expiry/timeout, which matters for a 1-120 second wait.

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?

Three short sentences, front-loaded with the action, then the side effect, then the alternative. Every clause carries information; nothing is redundant.

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?

No output schema exists, and the description does state the return value (the code) and its post-conditions, so the core is covered. Gaps remain around timeout behavior, the meaning of `site`, and disambiguation from wait_for_email_code — non-trivial for a side-effecting wait tool with zero annotation coverage.

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 only 33% — only identity_id is documented in the schema — yet the description explains neither `site` (which site/domain is polled?) nor how `timeout_seconds` affects the wait or what occurs if it elapses. With low coverage the description is expected to compensate and it does not.

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 concrete verb and resource ('Wait for an emailed verification code and return it') plus the agent condition it serves (browser runnerID can't reach). It does not, however, distinguish itself from the very similarly named sibling wait_for_email_code, leaving that confusion unresolved.

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?

'Prefer fill_email_code when you have a cdp_url' and 'for agents whose browser runnerID cannot reach' give an explicit selection rule against one alternative. It omits any guidance versus wait_for_email_code, the closest-sounding sibling, so the routing is clear but incomplete.

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