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

There are no annotations, so the description carries the full burden. It discloses test-mode-only behavior, the need for a Proof account, client authentication, and the start_login caveat. However, it does not explain side effects (e.g., whether the verification becomes permanently marked complete) or expected return behavior, leaving some behavioral ambiguity.

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 compact and front-loaded: the core purpose and constraint appear in the first sentence. The ACCESS note is purposeful and adds necessary operational context without unnecessary elaboration. Every sentence earns its place.

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 tool with one parameter and no output schema, the description covers the essential operational context: test-mode restriction, authentication prerequisite, and a common misuse warning. It could be slightly more complete by explaining where the verification ID comes from or what a successful call returns, but these are minor given the tool's simplicity.

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 100%, and the only parameter 'id' is adequately described as 'Verification ID.' The description adds no additional detail about how to obtain or format the ID, but the schema already carries the meaning, so baseline 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 states a specific action ('Auto-complete a verification'), the resource involved, and a critical scoping constraint ('pk_test_* API keys only'). It also explains the practical purpose (testing without real OTP delivery), which distinguishes it from normal verification submission tools.

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 explicitly says when to use this tool: for testing flows without real OTP delivery, and only in test mode. It also adds a clear exclusion by warning that 'start_login does NOT open this tool.' It does not name a specific alternative tool for non-test verification, but the mode-based guidance is sufficient.

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