agent_unread_count

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

With no annotations, the description carries the full burden of behavioral disclosure, and it falls short. It does not say whether counting is a pure read or affects read state (relevant given sibling agent_mark_read), whether auth is required, or how results are scoped; the credential-store sentence is confusing rather than informative.

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?

Only two sentences, but the second one is off-topic (identity/credential store) and does not earn its place; it introduces noise into an otherwise terse definition. The useful content is a single sentence.

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?

With no output schema, the 'per-sender breakdown' phrase usefully hints at the return shape, which partially compensates. But the misleading credential-store claim and the absence of any usage or behavior context leave real gaps for a messaging tool with an ambiguous read-state side effect.

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 100% and the single 'from' parameter is documented in the schema as an optional sender DID filter. The description's 'per-sender breakdown' loosely aligns with it but adds no format or semantics beyond the schema, so the 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?

The first sentence gives a specific verb+resource: counting unread messages, with a per-sender breakdown, which distinguishes it from generic siblings like agent_receive_messages or agent_mark_read. However, the second sentence ('Acts as the identity in the local credential store') is unrelated to counting and muddies the stated purpose, so it is not a clean 5.

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?

There is no statement of when to use this tool versus alternatives such as agent_receive_messages, agent_mark_read, or agent_analytics, nor any prerequisites or exclusions. The agent is left to infer usage entirely from the name.

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