actor_inbox_size

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

With no annotations, the description must disclose behavioral traits. It states it returns a count but does not mention that it is a read-only operation, does not destroy or modify the inbox, or whether it has side effects. For a query tool, this is a minimal expectation. The description is too brief to disclose non-obvious 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 a single, clear sentence with no verbosity issues. It is acceptably concise and front-loaded with the main action. However, it could use an additional sentence for usage guidance without becoming too long, so it earns a 4.

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?

The tool has a simple interface (one parameter, no output schema), but the description omits critical context: what the return value looks like (e.g., integer vs. formatted string), whether the inbox is cleared after reading, or any side effects like error conditions for invalid actorId. With no annotations or output schema, the description is insufficient for an agent to use the tool safely and correctly.

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 schema has 0% coverage, meaning the description must compensate for the undocumented 'actorId' parameter. The description mentions 'an actor's inbox' which implies actorId identifies the actor, but it does not clarify the format or identifier type (e.g., numeric ID, string name). Baseline is 3 because the description provides some context beyond the schema, but not enough to fully clarify the parameter.

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 that the tool returns the count of pending messages in an actor's inbox. It uses a specific verb ('Return') and resource ('number of pending messages in an actor's inbox'), which is distinct from siblings like actor_send_message and actor_broadcast that send messages.

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?

The description does not explicitly state when to use this tool versus alternatives, nor does it mention any prerequisites (e.g., 'Use this to check if an actor has pending messages before processing'). It only implies usage by saying 'Return the count'.

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