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

Annotations already cover safety (readOnly, non-destructive, closed-world), yet the description adds real behavioral context: the possible return states (pending/received/expired), what findings accompany a processed result, that processing failures surface as errors, and the access caveat that anyone with the test ID can retrieve it.

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?

Four sentences, front-loaded with the purpose before the status/findings detail and the security caveat. Each sentence carries distinct information; slightly dense but nothing is redundant.

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 compensates by enumerating return states, the findings payload when processed, and error behavior, plus the access caveat — everything an agent needs to call and interpret this read tool.

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's description already says it is 'the id returned by start_inbox_test.' The description repeats that provenance but adds no format or syntax detail beyond the schema, so the baseline 3 applies.

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 (Read) and resource (MailVakt email-receipt test), and explicitly ties itself to the sibling that creates the resource ('the ID returned by start_inbox_test'), distinguishing it from start_inbox_test at a glance.

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?

Explains how to obtain the ID (from start_inbox_test) and constrains use to IDs supplied by the user or created in this conversation, plus a scope exclusion ('Does not measure placement at other mailbox providers'). Clear context and an exclusion, though it doesn't spell out the full when-not workflow.

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