Usage Report

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. It explicitly states that it's purely local counters, records no URLs or page content, and can be disabled via an environment variable. It also discloses the file location. While it doesn't explicitly state it's read-only, the description implies no side effects beyond reading local data, which is good transparency.

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 two sentences, front-loading the core function ('Local usage stats') and then providing necessary privacy and configuration details. Every word earns its place; no fluff or redundancy.

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?

Given the tool has no parameters and an output schema exists, the description covers the essential aspects: what the report contains, its privacy guarantees, and how to disable it. The agent has enough information to understand when and how to call the tool 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?

There are zero parameters, so schema coverage is trivially 100%. The description adds context about the report content (tool call counts, per-day breakdown, totals), which is sufficient. Since there are no params, the baseline of 4 applies, and the description doesn't need to add more.

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 the tool's function: providing local usage statistics with specific details (tool call counts, per-day breakdown, totals). It distinguishes itself from the sibling browser tools by emphasizing it's local and about tool usage, not browser activity.

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 when to use it (for personal insight into tool usage) and notes it's local and purely for one's own benefit. It doesn't explicitly state alternatives, but the sibling set is overwhelmingly browser tools, making this tool's purpose unique. The lack of explicit 'when not to use' is a minor gap, but the intended use is clear enough.

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