call_stats

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

Without annotations, the description effectively explains the tool's server-side nature and contrasts with call_summary. It details return format and parameter behavior. However, it could be more explicit about potential limitations (e.g., max days, result size) and authentication requirements.

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 well-structured with a first-line summary, usage context, parameter list, and return format. It is concise but could be slightly tightened in parameter explanations. Overall, effective and efficient.

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 presence of an output schema in the description, detailed parameter semantics, and differentiation from siblings, the description is contextually complete. Minor gaps like error handling or edge cases are acceptable, as the tool is well covered.

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?

With 0% schema description coverage, the description fully compensates by explaining each parameter: group_by options, days default, start_date/end_date precedence, company_id filtering, fields as comma-separated metrics with default, and account_id auto-resolution. This adds significant meaning beyond the schema.

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 performs server-side call aggregation via a specific API endpoint, and explicitly distinguishes it from the sibling tool 'call_summary' (client-side pagination). This meets the highest standard of specificity and differentiation.

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 gives explicit guidance: 'prefer this over `call_summary` when you only need grouped totals', and notes when `call_summary` remains useful. This provides clear context and alternatives.

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