Take over a phone call

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

Annotations already declare destructiveHint=true, openWorldHint=true, and non-idempotent, so the safety profile is covered by structured data. The description adds only the precondition that the call must be 'connected'; it doesn't say what happens to the AI leg of the call, whether the transfer is reversible, or that the bot stops handling it.

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, action first, constraint second. Every word earns its place with zero filler.

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 tool whose annotations carry the destructive/open-world profile and whose schema documents callId, the description is nearly sufficient. The only missing piece is post-transfer behavior (that the call continues on the user's phone / the bot hands off), which would help an agent set expectations.

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 100% and the single callId parameter is fully documented in the schema, including its format and origin (start_call). The description adds no parameter meaning beyond that, so the baseline 3 applies.

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: 'Hand a connected phone call to the user's own phone.' An agent can tell this is not end_call or start_call, though the description never names those siblings explicitly, so differentiation is implied rather than stated.

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?

'Only when the user asks to take over' is an explicit precondition and a when-not constraint. It does not name alternative tools (e.g., end_call) or what to do if the call isn't connected, but the trigger condition is unambiguous.

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