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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds context by stating it 'propose[s] reviewed prefix repairs for confirmation,' indicating it is advisory and does not directly modify state, which aligns with the read-only hint. It also discloses a functional limitation (cannot determine network rejection), adding value beyond the annotations.

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 two concise sentences. The first sentence states the core function, and the second adds a key limitation. It is front-loaded and wastes no words, making it easy for an agent to quickly grasp the tool's purpose and constraints.

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?

Despite having an output schema, the description leaves out essential context for a tool with 7 parameters and 3 enums. It does not explain any parameter semantics, nor does it explicitly guide when to use this tool over its many siblings. The only usage cue is the limitation about network rejection, which is insufficient for an agent to fully understand when to invoke this tool.

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 0%, meaning the description provides no explanation of any of the 7 parameters. The description does not mention phoneNumber, symptom, detail, device, or any country code parameters. Since coverage is low, the description was expected to compensate but did not, leaving agents to rely solely on the schema's bare names and enums.

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 the tool explains formatting issues and proposes reviewed prefix repairs for confirmation, which is a specific verb+resource. It also adds a limitation (cannot determine why a network rejected a call), distinguishing it from related tools that might focus on network diagnostics. This is a precise purpose that differentiates it from siblings like analyze_phone_number.

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?

The description provides a clear when-not case ('Cannot determine why a network rejected a call') but does not explicitly name alternatives or conditions for when to use this tool over others. The purpose implies usage for formatting issues, but there is no explicit comparison to siblings like format_international_phone_number or analyze_phone_number.

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