msg_count

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

No annotations are provided, so the description carries the full burden of disclosing behavior. It only states what the tool does (counts messages) but does not mention whether it is read-only, what statuses it refers to, how results are returned, or any limitations. This is minimal transparency beyond the literal function.

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, front-loaded sentence with no filler words or redundant information. It conveys the essential purpose efficiently.

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 is simple (one parameter, no output schema), but the description leaves gaps: it does not specify what statuses are available, whether it returns counts per status or just a total, or the response format. Without annotations or an output schema, more detail would be expected for full completeness, yet the description is adequate for a basic counting tool.

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 100% since the only parameter 'agent' is described as 'Agent name'. The description reaffirms 'for an agent' but adds no substantial new meaning beyond the schema. Baseline 3 is appropriate because the schema already documents 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 uses the specific verb 'Count' with resource 'messages' and clear scope ('by status', 'for an agent'), which distinguishes it from sibling tools like msg_list_threads or msg_search. The purpose is immediately clear and unambiguous.

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 implies usage (when you need counts of messages by status) but provides no explicit guidance on when to use this tool over alternatives like msg_search or msg_activity_feed. No exclusions or alternative tool names are mentioned, so it only meets the 'implied usage' level.

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