List call detail records

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds substantial behavioral detail beyond that: cursor-based pagination semantics, absence of page numbers and total counts, the hard-error behavior for invalid cursors, the 50-record page cap versus the WARP API's 1000, and specific error codes. This is rich, non-obvious behavior that an agent needs to call the tool correctly.

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 dense but every sentence earns its place: action/scope, use cases, pagination behavior, sibling routing, and error codes. It is front-loaded with the core purpose, then expands into operational details.

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?

For a paginated list tool with nine parameters, no required parameters, no output schema, and annotations covering safety, the description is complete. It explains how pagination works, when to stop, what not to expect ('no page number and no total count'), and what errors may occur. An agent has everything needed to invoke and consume this 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?

Schema coverage is 100%, so the schema already documents every parameter, giving a baseline of 3. The description adds meaningful semantics beyond the schema, especially for cursor ('pass the previous response's next_cursor back'), the lack of page numbers/total counts, and the limit behavior. It doesn't deeply elaborate on each filter, but the schema already does that.

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 states a specific action ('List call detail records') on a specific resource (CDRs), with scope (date range, optional filters) and ordering ('newest first'). It names concrete use cases and explicitly distinguishes itself from cdr_get_statistics and cdr_get_trends, so an agent can tell it apart from siblings.

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 when-to-use guidance ('investigate specific calls, verify traffic, or debug call failures') and explicitly names alternatives for other needs ('For aggregate metrics use cdr_get_statistics; for chart data use cdr_get_trends'). This leaves little ambiguity about tool selection.

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