read

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

Given readOnlyHint=false and idempotentHint=false, the key disclosure is exactly what the description provides: the message is marked read if addressed to you, explaining the non-read-only, non-idempotent behavior. It also explains that attachments resolve to local paths and that images are returned after the text, which is genuine value beyond the annotations; it stops short of saying whether marking read is reversible or visible to the sender.

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 behavioral sentence is front-loaded and the whole thing is short. The Args block repeating "message id" for a single required string param is mild redundancy but harmless.

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?

An output schema exists, so return values needn't be spelled out, yet the description helpfully previews attachment handling. Combined with the side-effect disclosure, an agent has what it needs to invoke it; only the source of the id and the visibility of the read-mark remain unstated.

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% and the only parameter is documented solely as "id: message id," which mostly restates the property name. It does clarify that the id refers to a message rather than a thread, but adds no format or provenance guidance (e.g., where to obtain the id).

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?

States a specific verb and resource ("Read a message in full") and even names the side effect (marked read when addressed to you). It is distinguishable from list-oriented siblings like inbox, search, and summary, though it never names those alternatives explicitly.

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?

Usage is only implied: you need a message id, which suggests reading a specific message found via inbox or search. There is no explicit statement of when to prefer this over inbox/search, nor any precondition about which messages are readable.

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