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

There are no annotations, so the description carries the burden. It adds useful access context and the 'in-progress' constraint, but it does not explicitly state that this is a read-only/idempotent operation or describe session lifecycle or return behavior.

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 the core purpose, followed by an access note. The access note is slightly awkward ('a session opens this tool') but still earns its place by covering an important prerequisite.

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 simple status-check tool with one parameter and no output schema, the description is mostly adequate. It could be improved by naming start_add_email as the session-creation counterpart and by hinting at what status values the caller might expect.

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 single parameter is documented as 'Add-email session ID.' The description adds minimal extra meaning beyond 'by session ID,' which matches the baseline for fully covered schemas.

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 states a specific verb and resource: 'Check the status of an in-progress email addition by session ID.' This is precise and distinguishes the tool from related siblings like get_add_phone_status and list_emails.

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 clearly implies this tool is used after an email-addition flow has been initiated and provides explicit auth prerequisites ('needs a Proof account', 'Authenticate this client... or sign in with start_login'). It does not explicitly name alternatives, but the usage context is clear.

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