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

Annotations already declare readOnly, idempotent, and non-destructive, so safety is covered. The description adds useful negative disclosures (no media credentials, no cost estimate) and a self-only access scope, which is real value, but it omits what status values are returned or whether results change as the call progresses.

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?

Two short sentences with the resource front-loaded, so it is efficient. The second sentence is cryptic ('a guessed running cost') and its relevance is unclear without context, so not every clause clearly earns its place.

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?

There is no output schema, so the description is the only place to learn what a 'status' contains, and it never enumerates possible states (ringing, active, ended) or the shape of the response. For a status-inspection tool with zero schema coverage and no annotations about returns, this leaves the agent guessing at the primary output.

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 single parameter callId has no schema description (0% coverage), so the description carries the full burden. It only hints that the id refers to a 'call invite' but never says where the callId comes from or whether it accepts a session id versus a booking id, leaving the one required input ambiguous.

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 identifies the resource (a call invite/session) and implies a status read, plus an access scope ("where you are the caller or the expert"). But it never uses an explicit verb like 'retrieve' or 'get', and it does not distinguish itself from near siblings such as list_my_calls, estimate_call_cost, or end_call, 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?

There is no statement of when to call this rather than list_my_calls or estimate_call_cost, and no prerequisites (e.g., an active invite or callId obtained from start_call) are given. The only guidance-like content is a negative about return values, which is behavioral rather than usage.

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