subagent_message

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

With no annotations, the description carries the full burden and does disclose the non-obvious dual-mode semantics: same tool either injects into a live job (requiring reply_to when answering) or spawns a continuation job after completion, returning that job. It omits what the live-path call returns, queueing behavior, and error cases, which keeps it from a 5.

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 clauses, front-loaded with the verb and resource, then the two timing branches. Telegraphic fragments ('While it runs:', 'After it finished:') are slightly rough but every clause carries information.

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 3-parameter tool with no annotations and no output schema, the description covers timing and continuation behavior but leaves the live-path return value and failure modes unstated. An agent can call it, but cannot predict the response shape in the while-running case.

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 67%; the description adds real meaning beyond the schema by tying reply_to to answering a question and by explaining that job_id refers to a running subagent in one branch and a finished one in the other. Only 'text' is left entirely to the 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 and resource ('Send a message to a subagent') and then characterizes two distinct behaviors, which separates it from siblings like subagent_start. It doesn't explicitly name an alternative tool, but the mode descriptions make the distinction inferable.

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 clear state-based guidance: use it while the subagent runs for a follow-up or to answer a question, and after it finishes to continue the conversation as a new job. No explicit exclusions or named alternatives, so it stops short of a 5.

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