turn

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

With no annotations, the description carries the full burden. It usefully discloses a persistent side effect ('stores both word for word') and a read component ('returns what Commons already knows'), but says nothing about auth (despite an api_key parameter), rate limits, ordering, or idempotency of the required every-turn call.

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?

Roughly two sentences, front-loaded with the core instruction and invocation example. Efficient, though the parenthetical syntax example is slightly crowded.

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?

A 6-parameter tool with zero schema coverage, no annotations, and no output schema demands far more than this description provides. Auth, the four undocumented parameters, and behavior of the returned knowledge are all absent.

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 0% across 6 parameters, so the description must compensate. It only documents two of them (user_message, reply) and even those without real semantics, leaving agent, api_key, project, and conversation entirely unexplained.

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 states a specific dual function (store the exchange word-for-word and return what Commons already knows about the message), which is meaningful. However, 'turn' is an opaque name and the framing ('Chat apps without hooks') is confusing rather than clarifying. It does not differentiate from the many sibling messaging tools (msg_send, msg_recv, msg_get), leaving the agent to guess the relationship.

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?

It gives explicit timing guidance: 'call on EVERY turn, before answering,' which is exactly the when-to-use context an agent needs. It stops short of naming alternatives or stating when NOT to call it (e.g., once a hook exists), so it falls just shy of a 5.

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