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

Annotations only cover the safety profile (non-readOnly, openWorld, non-destructive). The description goes well beyond that, disclosing the async lifecycle, immediate return of job_id/status/poll URLs, the inline-completion case for small lists, and the webhook notification path — exactly the behavioral context an agent needs to drive the workflow.

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?

Three tight sentences, front-loaded with the primary purpose and immediate return, then the polling workflow, then the optional webhook. Every sentence earns its place with no redundancy.

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?

With no output schema, the description correctly compensates by describing the return payload (job_id, status, check_status_url, results_url) and the two terminal states. Combined with the follow-up tool names, an agent has everything needed to submit and complete the job.

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 both parameters are self-documenting, so the schema does the heavy lifting. The description adds only the 'public HTTPS' constraint on webhook_url, which the schema already states, and the server-side dedupe note already appears in the schema. 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?

States a specific verb (submit), resource (list of email addresses), and mode (asynchronous bulk verification job), and explicitly scopes it as 'the right tool for large lists.' This lets an agent distinguish it from verify_email and verify_batch without opening a schema.

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?

Clearly routes the agent: use for large lists, poll get_job_status until 'completed', then call get_job_results. It names the follow-up siblings and the webhook alternative. It stops short of stating when NOT to use it (e.g., preferring verify_batch/verify_email for small lists), so a 4 rather than 5.

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