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

The annotations already state that the tool is not read-only, not destructive, not idempotent, and not open-world. The description adds useful context that no carrier settings change, number purchase, or phone call occurs, and that test verification requires linked call evidence, but it still does not explain what is mutated, what permissions are needed, or what the operation returns.

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 short and front-loaded, with no obvious filler. The three sentences each contribute a constraint or scope note, though "canonical service" remains ambiguous.

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 three-parameter mutation tool with no output schema and no parameter descriptions, the definition is missing key operational details: what instructions are recorded, how base_revision is used, what project_id scopes, and what the result looks like. It does not provide enough for an agent to invoke the tool confidently.

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 burden for all three parameters. It only loosely implies setup_id through "existing-number forwarding setup" and provides no meaning for base_revision or project_id, leaving required concurrency and scoping parameters 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 identifies the resource (an existing-number forwarding setup) but uses the vague verb "manage" and does not clarify whether this creates, updates, or otherwise records forwarding instructions. It also does not distinguish the tool from close siblings such as update_forwarding_setup, get_forwarding_instructions, or create_forwarding_setup.

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?

There is no explicit guidance on when to use this tool versus alternatives like update_forwarding_setup or get_forwarding_instructions. The statement "Test verification requires linked call evidence" hints at a condition, but it is not framed as usage guidance or exclusion criteria.

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