Claude Code: Tool Histogram

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

Annotations fully cover read-only, open-world, idempotent, and non-destructive traits. The description adds only the default time window, which is a minor behavioral detail. No additional traits (e.g., return format, pagination) are disclosed, but annotations already provide strong safety signals.

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?

Description is one sentence, immediately stating the tool's purpose and a key behavioral detail (default window). No wasted words; every part contributes value.

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 one well-documented parameter, comprehensive annotations, and no output schema, the description is largely complete. It communicates the core function and default behavior. Could mention that it returns counts per tool, but this is implied by 'histogram.'

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 single parameter 'since' is fully described in the schema with examples. The tool description adds the default value of 6 hours, which provides useful context beyond the schema. With 100% schema coverage, this extra default information elevates the score.

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?

Description clearly states the tool provides a histogram of Claude Code tool usage, specifying the resource ('tool-use') and verb ('histogram'). The title and description together distinguish it from sibling tools like claude_errors or claude_recent, which focus on different aspects.

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 mentions a default time window ('Default 6h') but does not explicitly guide when to use this tool versus alternatives. Usage context is implied (when you need tool usage counts), but no exclusions or sibling comparisons are provided.

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