use_phone

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

With no annotations, the description carries the disclosure burden. It transparently reveals the key side effect: changing the default affects everyone on the server. It does not mention other behaviors like validation or reversion, but for a single-parameter setter this is adequate and not misleading.

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 sentences, front-loaded purpose, and a clear warning in the second. Every word earns its place; no padding or redundant schema repetition.

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 tool with one required parameter and an output schema, the description covers purpose, global side effect, and usage guidance. It does not list possible values or error cases, but the presence of sibling tools like list_phones mitigates this gap. Overall complete enough for correct invocation.

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 0%, so the description must clarify the parameter. It implies the parameter is a phone name ('Set which phone'), but never explicitly connects the 'name' field to a valid phone identifier or its format. An agent would still need to infer the meaning from the tool name and context.

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 states a specific action (set default phone) and resource (the phone used by other tools when no device is named). It clearly differentiates from siblings by focusing on context-setting rather than phone actions or management.

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?

Explicitly explains when to use (set a global default) and when not to (when switching between phones, prefer naming per call). Warns about the global effect on all server users, which is a strong usage guardrail.

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