join_run

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

With no annotations, the description carries the full burden. It discloses the return format ('Returns: {"island": int}') and error structure, and the warning about not inventing assignments implies that the tool assigns islands automatically. It lacks mention of side effects like marking the worker as joined, but covers key behavior.

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?

The description is compact and front-loaded, with each sentence serving a purpose: action, timing, parameter hint, return format, and a caution. No redundant or vague statements.

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 tool with only 2 required parameters and no enums, the description covers all essential aspects: what it does, when to call it, how to use parameters, and what it returns/errors. The output schema also exists, so return value details are already structured. The description is complete for this tool's complexity.

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?

The description elaborates on the 'runtime' parameter ('Pass a useful runtime label such as claude-code, codex, or a local worker identifier'), but 'run_id' is only implied by 'Join a run' and the reference to get_contract. Given 0% schema description coverage, it partially compensates but leaves run_id underspecified.

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?

The description clearly states the specific action ('Join a run') and the result ('receive this worker's island assignment'). It distinguishes itself from siblings by placing it in a workflow ('after get_contract and before the first next_parent call').

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?

Explicitly provides sequencing context ('Call this after get_contract and before the first next_parent call') and a mistake to avoid ('never invent an island number or reuse another worker's assignment'), which effectively tells the agent when and how to use the tool.

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