get_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it does this well. It explicitly warns about the side effect of marking the message as read, and alerts the agent that the html field is attacker-controlled and must not be rendered directly. This is critical behavioral and security context beyond the tool name and schema.

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 sentences with no filler. The first sentence states the primary function, the second discloses the side effect, and the third provides a necessary security warning. Each sentence earns its place and the most important information is front-loaded.

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 single-parameter tool with no output schema, the description covers the essential context: what the tool returns, the side effect of reading a message, and a safety caveat about untrusted HTML content. An agent has enough information to invoke it correctly and handle the response appropriately.

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 has 100% description coverage for the single required id parameter, which already explains that it comes from list_messages or get_thread. The description adds no additional parameter semantics beyond referring to 'one message,' so the baseline score 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-resource pair ('Get one message's full content') and specifies exactly what is included: text/html body and attachment metadata. This clearly differentiates it from sibling tools like list_messages, which lists messages, or get_thread, which returns an entire thread.

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 usage: use it when you need the full content of a single message. However, it does not explicitly state when to avoid it, mention alternatives, or contrast it with list_messages or get_thread. The context is clear but left to inference.

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