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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals a non-obvious behavior: the tool does not actually recover the key automatically; it only guides toward staff contact. This is meaningful transparency, though the exact output or side effects of using the phone number are not detailed.

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 sentences with no filler. It front-loads the primary purpose and then adds the important security caveat. Every word contributes to understanding the tool.

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?

The description is adequate for basic selection and invocation, but it leaves gaps: it doesn't explain what 'guides you to contact staff' actually returns or what next steps look like, and it doesn't clarify how the phone number is used. Still, the tool is simple, and the single-parameter schema limits the impact of these gaps.

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%, and the phone parameter is already described as the 'Phone number used at registration.' The tool description adds no further meaning beyond that, so the baseline score of 3 is appropriate.

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 identifies the operation (recovering a lost customerKey) and the resource involved, and it clarifies that automatic recovery is not available. It doesn't explicitly contrast itself with sibling tools, but the intent is unambiguous.

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?

It gives clear context: use this when a customerKey is lost, and for security reasons automatic recovery is not offered. It explains that the tool guides the user to contact staff, which helps set expectations even if it doesn't explicitly list sibling alternatives.

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