ACTION_GET_CALL_STATE

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

With no annotations supplied, the description usefully discloses the required permission, the four output variables, all call-state values, and the variable-snapshot JSON return form. It could further explain what happens when permission is denied and how call_success and call_error are populated.

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?

The purpose and permission requirement are front-loaded, followed by compact output definitions and return-format details. The text is efficient overall, though the duplicated punctuation and generic interpolation boilerplate slightly reduce polish.

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 simple read tool with no required parameters or annotations, the description supplies the key permission, state vocabulary, output names, and return representation needed to invoke and interpret it. The input schema separately covers assertion, error handling, and timeout controls, leaving no major invocation gap.

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 already 100%, so the three workflow-control parameters need little additional explanation. The description nevertheless adds useful invocation semantics not present in the schema by stating that string parameters support ${var} interpolation.

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 clearly states that the tool reads the current phone call state, and the idle/ringing/offhook mappings clarify its exact scope. It does not explicitly distinguish this instantaneous state read from siblings such as ACTION_WAIT_CALL_ANSWER or ACTION_WAIT_CALL_END.

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?

Usage is implied for inspecting the call state at the current moment, and the READ_PHONE_STATE permission prerequisite is stated. However, there is no explicit guidance on when to use this tool rather than waiting for call events or reading related device audio state.

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