Session Stats

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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is clear. The description adds the list of reported metrics, which is useful but overlaps with the output schema and does not disclose other behavioral traits (e.g., refresh cadence or whether the stats are real-time). With annotations covering safety, a 3 is appropriate.

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 that enumerates the metrics efficiently. It is dense but not wasteful, though a brief introductory verb (e.g., 'Returns') would make it slightly more scannable.

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 a zero-parameter read-only tool with an output schema and clear annotations, the description is sufficiently complete: it tells the agent what categories of data are available. It could be improved by specifying when to call it, but that is covered under usage guidelines.

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 the baseline is 4. The description adds no parameter semantics because none exist, but the schema is empty and needs no further explanation.

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 indicates this tool returns session usage statistics, enumerating the specific metrics (calls, errors, latency, cost, budget, zone status, browser sessions). The resource and scope are identifiable, and the sibling tools (scraping/extraction) are unrelated, so no differentiation is needed.

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?

Usage is only implied: an agent would infer this is for checking session health and cost. There is no explicit when-to-use guidance, no mention of alternatives, and no exclusions. It is adequate but minimal.

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