get_email_by_id

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

Annotations already provide readOnlyHint=true, setting the safety baseline. The description adds valuable behavioral context: the response includes a security block (dkim/spf/dmarc pass-fail, Proton's spam score/action, encryption metadata) for phishing triage. It also warns about not constructing the emailId manually. No contradictions with annotations.

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 three tightly written sentences. The first states the action, the second gives usage context, and the third discloses the security block. Every sentence earns its place with zero redundant phrasing.

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 tool with four parameters and no output schema, the description covers the key facets: the composite ID format, usage sequence, and the security block in the response. It could be more explicit about the full return structure (e.g., standard email fields), but 'full content' plus the detailed schema descriptions for preferHtml and showHeaders provide adequate context.

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%, so the baseline is 3. The description enhances the emailId parameter by explaining the format 'FOLDER::UID' and reinforcing that it must come from a prior tool call. This adds meaning beyond the schema's terse 'Composite email id from previous tool output.'

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 opens with a specific verb and resource: 'Fetch the full content of a single email using a composite emailId.' It also distinguishes itself from siblings by stating 'Use after get_emails or search_emails to read a specific message in full,' making the tool's purpose unambiguous.

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?

Explicitly states when to use: 'Use after get_emails or search_emails to read a specific message in full.' It also gives a critical usage caveat: 'always use the id returned by a prior tool call; do not construct it manually.' It does not explicitly mention alternatives like get_emails_by_ids, but the context is clear.

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