read_email

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

Goes well beyond the annotations: it discloses that the read does not mark the message read, that only plain text plus attachment names/sizes are returned (no HTML, images, links, or downloads), the character semantics of body_offset, the limit defaults/caps, and a prompt-injection warning about untrusted email content. This is exactly the behavioral context annotations cannot convey.

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?

Front-loaded with purpose and the non-mutating guarantee, then pagination mechanics, then the security caveat. Every clause carries distinct information; nothing is restated from the schema or annotations.

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 paginated single-message reader with an output schema, the description supplies everything an agent needs: limits, offset semantics, how to continue pagination, what the body excludes, and a safety note about untrusted content. No material gap remains.

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?

With 0% schema description coverage the description must carry the load, and it largely does: body_offset is defined as counting Unicode characters, body_limit gets its 12000 default and 30000 max, and the two IDs are characterized as opaque. It stops short of explaining server-side error behavior for invalid IDs, but the semantic gaps are covered.

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+resource ('Read an email by opaque entry_id and store_id') and immediately carves out scope that distinguishes it from siblings like search_emails and recent_emails: single-message read with no read-state mutation. An agent can route to it without inspecting the 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?

Usage context is implied by the requirement of an opaque entry_id/store_id and by the non-mutating read behavior, plus explicit pagination guidance (follow next_body_offset while body_truncated). However, it never names alternatives such as search_emails or recent_emails, so there is no explicit when-to-use-this-vs-that routing.

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