List call records

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds genuinely useful behavior beyond that — newest-first ordering, a stateless pagination model with 'nothing is saved between calls', and the contents of the summary block. It does not cover rate limits or the default date range.

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?

Dense but front-loaded: the core operation, ordering, pagination model and summary contents come before the optional-filter detail. It is a single run-on paragraph rather than a violation of length.

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 no output schema, the description usefully enumerates the summary fields (total, answered, answer rate, duration, cost) and explains the stateless pagination contract for an 11-parameter tool. It omits default date-range behavior when dates are absent, which is the main remaining gap.

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 82%, so baseline is 3, and the description adds real meaning: the 92-day max span for start_date/end_date and concrete hangup_cause values (NORMAL_CLEARING = answered, NO_ANSWER, USER_BUSY) that the schema only constrains by pattern. Minor confusion is introduced by advertising 'limit/offset' when the schema exposes only page/per_page.

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?

States a specific verb and resource with scope: 'List completed call records (CDRs) for this account, newest first.' The word 'completed' implicitly separates it from list_live_calls and get_call_details, but no sibling is named explicitly, so an agent must infer the boundary.

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?

Gives filter-oriented guidance ('Filter by hangup_cause ... to find answered, missed or busy calls'), which implies usage, but never states when to choose this tool over list_live_calls, get_call_details, or get_call_recording, and offers no exclusions.

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