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

destructiveHint=true already flags the mutation, but the description adds substantive context the annotation cannot: the termination affects every participant, and there is a two-phase preview/execute safeguard tied to confirm. It stops short of stating who is permitted to end a call or what happens to a call already ended.

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?

A single tight sentence with the scope statement first and the confirm-gating caveat second. Nothing is padded.

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 two-parameter destructive tool with no output schema, the description covers scope and the safety gate, which is what an agent most needs. It leaves open authorization requirements and post-call state, a modest gap rather than a blocking one.

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 confirm parameter is fully described in the schema already, so the description's confirm mention adds little; callId, the required parameter and half of the 50% coverage gap, gets no explanation of what identifier it expects (session id, room id, gym class id). Baseline 3 for partial coverage with the required param left 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?

States a specific verb and resource plus the blast radius ('for everyone'), which cleanly separates it from start_instant_video_call and the join_*_video_call siblings. An agent can pick this out without opening the schema.

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 explains the confirm-gated workflow ('previews until confirm: true'), which is real invocation guidance, but it never says when to end a call versus leaving it or which sibling tools relate to the same call lifecycle. Usage context is implied rather than stated.

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