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

Annotations already cover read-only, idempotent, non-destructive behavior, so the description's added value is in disclosing two real traits: authorization scoping (other people's calls are not found) and an output limitation (recording URLs are not included). That is meaningful context beyond the annotations, though it doesn't say what happens on not-found or what the receipt contains.

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?

Three short sentences, purpose front-loaded, no filler. Each sentence delivers a distinct fact: what it returns, who can access it, and what is excluded.

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 one-parameter read tool with rich safety annotations and no output schema, the description covers scope and exclusions adequately. It still leaves the parameter source and the receipt's contents unexplained, which an agent would need to call it confidently.

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 description coverage is 0% for the single callId parameter, so the description carries the burden. It only implies via 'one of your calls' that the ID must belong to the caller; it never says where to obtain the callId or what form it takes.

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 the resource (a receipt) and scope (one of your calls), which is clear enough to distinguish it from siblings like list_my_calls or get_call_session. It does not use an explicit verb and does not name a sibling alternative, keeping it short of a 5.

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?

'Other people's calls are not found' gives a useful exclusion, implying this tool only works for calls the caller owns. However, it never says when to reach for this versus get_call_session or list_my_calls, so routing guidance is only implied.

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