read_email

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

With no annotations, the description carries the full burden. It discloses read-only behavior ('never sends, drafts against, or mutates real mail'), auth requirements (RADMAIL_API_KEY), the fallback behavior when the key is missing (returns setup instructions), and the safety handling of untrusted email content. This goes well beyond the basic fetch behavior.

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 front-loaded with a clear purpose, but it is verbose and repetitive. For example, the immutable 'human-only forever' hard-stop is restated multiple times, and the safety block's content is described twice. Some sentences add redundant emphasis rather than new information.

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?

The description covers purpose, authentication, error behavior (setup instructions vs. error), and return content (headers + textBody). Without an output schema, it gives a high-level view of the response but does not detail the full response structure or possible errors beyond the API key case. It also mentions the `safety` block, which is helpful. Overall, it is complete enough for a single-fetch 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 67%, so the description is not required to fully compensate. It adds meaning to the required 'id' parameter by explaining it comes from a search hit's messageId. However, the 'focus' parameter is not described in the schema or the description, and the description does not elaborate on 'agentId' 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 clearly states the verb (fetch), the resource (one full email), and the scope (by id from a search hit). It distinguishes read_email from siblings like search and list_right_now by specifying that it fetches a single email using a messageId.

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?

It explicitly says 'use a `search` hit's messageId', which tells the agent when to call this tool (after a search). It does not name alternatives or exclusions, but the context is clear enough to differentiate from listing or drafting tools.

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