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

The description clearly indicates this is a read-only operation (consistent with readOnlyHint=true) and details the filtering capability, including the list of all filterable fields. It does not disclose any destructive behavior, which 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 purpose is stated concisely at the beginning. The description embeds a large JSON object listing all filterable fields, which is structured but adds length. It is front-loaded with the main activity, earning a high score for clarity despite verbosity.

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 read-only annotation, the presence of an output schema, and comprehensive parameter schema description, the tool description fully covers what the agent needs. No return value explanation is required, and pagination/filtering details are present.

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?

The schema has 100% coverage with descriptions for page, sort, limit, and filters. The description adds a comprehensive JSON of field names and types for filtering, providing significant additional context beyond the schema, though the lengthy list may overwhelm.

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 fetches call detail records from VoIPstudio, listing specific attributes (duration, cost, disposition) and that it supports filtering. This distinguishes it from sibling tools like get_live_calls or get_history_for_number, which deal with other aspects.

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?

While the description mentions filtering and lists fields, it does not provide explicit guidance on when to use this tool versus its alternatives. It lacks 'when to use' or 'when not to use' contexts, leaving the agent to infer usage from the tool name alone.

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