export_email

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

Annotations only include destructiveHint=false, so the agent knows it is not destructive. The description adds valuable non-obvious context: the tool writes raw RFC822 content to disk and requires an environment variable to be set. It does not contradict annotations, and the extra behavioral details (e.g., .eml format, backup use) go beyond what structured fields provide.

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 two sentences, front-loaded with the core action and immediately providing use-case and configuration context. Every sentence adds value, and there is no redundant or filler content.

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 2-parameter export tool with no output schema, the description covers purpose, use case, and a configuration prerequisite. It does not explicitly state what happens when outputPath is omitted, but the schema already marks it optional. Given the low complexity and strong schema coverage, the description is nearly complete.

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?

The input schema already describes both parameters (emailId in FOLDER::UID format, outputPath as optional file/directory). The description does not add much parameter-specific semantics beyond mentioning the .eml extension and the environment variable requirement. With 100% schema coverage, the baseline of 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 uses a specific verb ('Save') and resource ('full raw source (RFC822/.eml)') and clearly states the intended use case ('backup or migrating a message elsewhere'). This distinguishes it from sibling tools like save_attachment (which saves only attachments) and import_email (which brings messages in).

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 states when to use the tool ('Use for backup or migrating a message elsewhere') and provides a critical prerequisite (PROTONMAIL_ALLOW_FILE_DOWNLOAD_DIR configured, same as save_attachment). It does not explicitly state when not to use it or compare against alternatives, but the context is clear enough for an agent to select it appropriately.

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