whatsapp_reject_call

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

Annotations already declare this as a non-readOnly, idempotent, non-destructive write. The description adds genuinely supplementary behavior: the caller visibly sees the call declined and the operation fails outside the ringing window. It also notes the success-confirmation return.

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 tight sentences: action first, then parameter origin, then the timing constraint and return. Every sentence 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 two-parameter mutation tool with no output schema, the description covers the action, parameter origin, timing precondition, and return shape. It gives enough for correct invocation, though it could note the idempotency guarantee already implied by annotations.

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%, so the baseline is 3, but the description adds sourcing value by tying both IDs to the call_offer event, helping the agent locate the correct values rather than treating them as arbitrary strings.

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+resource ('Reject an incoming WhatsApp call') with scope and no ambiguity. No sibling tool overlaps with call rejection, so an agent can select it unambiguously from the list.

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?

Gives clear context for use ('using the callId and callerId from the call_offer event') and a hard precondition ('Only works while the call is still ringing'). It does not name an explicit alternative (e.g., answering), but the usage window is well-defined.

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