Make Phone Call

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

The description goes well beyond the annotations (readOnlyHint=false, idempotentHint=false, destructiveHint=false). The explicit '⚠️ WARNING: This initiates a REAL phone call. Verify the number before calling.' discloses a real-world side effect with irreversible social consequences — exactly the kind of behavioral context annotations cannot express. It also reveals the step-by-step UI manipulation and the dependency on a connected phone.

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 description is well-organized with a front-loaded purpose, then mechanism, then a prominently placed warning, plus an explicit Returns block. The Args section is mildly redundant with the schema, but the Returns block earns its place since no output schema exists. Minor redundancy keeps it from a 5.

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 single-parameter tool, this is nearly complete: it provides the return shape ({ initiated, phone_number }) compensating for the missing output schema, discloses the real-call risk, and explains the internal steps. Remaining gaps are failure/edge behavior — what happens if the phone is disconnected, the number is invalid, or the call is declined — and any prerequisites for the phone link being active.

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 description coverage is 100% — the schema already documents phone_number as 'The phone number to call (with country code if needed).' The description's Args section largely duplicates this, adding no new format, validation, or edge-case semantics. Per the rubric, baseline 3 applies when the schema does the heavy lifting, and that is the case here.

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 opening line 'Initiate a phone call through Phone Link's dial pad' states a specific verb and resource, and the mechanism ('Opens the Calls tab, enters the phone number, and clicks the call button') makes the action unambiguous. It clearly distinguishes itself from sibling get_* tools (read-only), phonelink_send_message (texting), and phonelink_launch_app (app launching) — it is the only tool that places a real call.

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 rather than stated: the description clarifies this triggers a real call from the connected phone, so an agent can infer when it applies and that it is not a simulation. However, there is no explicit when-to-use/when-not-to-use guidance, no named alternative (e.g., 'use phonelink_send_message to send a text instead'), and no prerequisites such as requiring the phone to be linked and online.

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