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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavioral context: the returned instructions must be executed by the user or carrier, and Patch cannot perform activation remotely, which prevents the agent from promising an automated result.

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 tight sentences with zero filler: the first states what is returned, the second states the critical constraint. Front-loaded and appropriately sized for the tool's simplicity.

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?

An output schema exists, so return value detail is not needed, and the key constraint (no remote activation) is disclosed. Still, for a 3-parameter tool with no schema descriptions, the description omits what 'mode' selects and whether 'number_id' is the Patch number or the existing carrier number, which materially affects 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 description coverage is 0%, so the description must carry the parameter burden and it largely does not. 'Carrier-specific' loosely hints at the provider parameter, but neither 'mode' (missed vs. all) nor 'number_id' is explained, leaving the most consequential enum undocumented.

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 uses a specific verb and resource ('Get carrier-specific steps for forwarding an existing phone to an owned Patch number') and makes the outcome concrete. It does not explicitly distinguish itself from close siblings like get_forwarding_carrier, so it stops short of a 5.

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 by the scenario ('forwarding an existing phone to an owned Patch number'), and the note that Patch cannot activate forwarding tells the agent this is an informational step, not an action. However, no sibling is named and there is no explicit when-not guidance relative to get_forwarding_carrier or update_phone_number.

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