Message a teammate's live session

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

Adds real behavioral context beyond the annotations: delivery is interleaved with the teammate's work ('between steps'), so it's a live, non-durable channel, and there is an explicit safety constraint against secrets. Open-world and non-idempotent hints are consistent with sending to people, but the description doesn't say what happens if no live session exists.

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 and delivery mechanism, then purpose, then the safety rule. No filler or repetition.

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 fully documented schema and no output schema, the description supplies the missing conceptual context: who receives it, when it lands, and the secrets prohibition. Gaps remain around failure modes (no live teammate, message length limits) and whether a response is returned.

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 100%, and every parameter (to, kind, reply_to, wait_seconds) is documented in the schema itself. The description only reinforces brevity ('short message') and the secret prohibition, adding little parameter-level meaning. Baseline 3 applies.

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 and resource (send a short message) plus the delivery target: a teammate's live agent, reaching them between steps. That distinguishes it from a durable comment or inbox check, though it never names the sibling it differs from (e.g. comment_on_session, check_live_inbox).

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?

Gives concrete when-to-use contexts: flag a change that affects them, ask a question, answer theirs — plus a clear safety rule ('Never include secrets'). It stops short of explicit exclusions or naming alternative tools for durable/asynchronous communication.

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