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

The description states 'This writes mail,' which aligns with readOnlyHint=false and adds explicit write behavior. It also discloses that it does not wait for MX, providing a behavioral detail beyond annotations. The test-focused nature is disclosed. No contradiction with annotations; idempotentHint=true is consistent with a store operation.

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?

Two concise sentences that front-load the primary purpose and key behavioral traits. No unnecessary words or repetition.

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?

Given the tool has 7 parameters (2 required) with no schema descriptions and no output schema, the description is far from complete. It lacks any guidance on how to fill the parameters, what attachments entail, or what the return value is. The description covers only the high-level purpose and a few behavioral traits, leaving agents to guess parameter semantics.

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 description coverage is 0%, so the description must explain parameters, but it mentions none. It does not clarify what inbox_id, from, subject, text, html, client_id, or attachments mean, nor their requirements or formats. The description adds zero parameter value.

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 tool's purpose: 'Store a test inbound message in the inbox without waiting for MX.' This is a specific verb+resource (store message) and distinguishes it from outbound sending tools like cooper_send_message. It also clarifies it's for tests by contrasting with production inbound via Cloudflare Email Routing.

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 implies when to use it: for test inbound messages, without waiting for MX. It contrasts with production inbound, giving context on the testing scenario. However, it does not explicitly name alternative tools like cooper_send_message or state when not to use it, but the test vs production distinction provides clear usage guidance.

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