Read a draft

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior. The description adds useful behavioral detail beyond that: the draft is decoded like get_message, HTML is returned only on request, and attachment metadata is included. It does not contradict the 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 two sentences with no filler. The first sentence front-loads the core behavior and return contents, and the second sentence delivers actionable usage context and an important warning. Every clause earns its place.

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 read-only tool with one required parameter, the description covers what the tool returns, how it behaves, when to use it, and why it matters before update_draft. The annotations cover safety and idempotency, so nothing important is missing for an agent to invoke it correctly.

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 adds some context by noting that include_html controls whether HTML is returned and that text body may exist, but it does not materially explain draft_id or max_body_chars beyond what the schema already states.

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 states a specific verb ('Fetches one draft'), a clear resource ('draft'), and enumerates what is returned (headers, text body, HTML on request, attachment metadata). It also distinguishes itself from get_message by explicitly modeling on it while targeting drafts, so an agent can select it without confusion.

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 provides explicit usage guidance: use it to show what send_draft would send, or to read current content before update_draft. It even warns that updates REPLACE the whole draft, giving a concrete reason to call this tool first. This clearly frames when to use it relative to its sibling tools.

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