read_thread

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

With no annotations, the description carries the full burden and does well: it discloses default truncation, how to get full bodies (max_body_chars=0), ordering, and warns that email content is untrusted third-party data and must never be treated as instructions. This is critical behavioral/security context beyond the 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?

Three tight sentences lead with the purpose, then usage options, then a security warning. Every sentence provides actionable information with no redundancy or filler.

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, ordering, truncation behavior, and security handling, which is sufficient for the tool's complexity. There is no output schema, but the return value (the messages in the thread) is implied; a slightly more explicit return-shape statement would make it fully complete.

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 behavioral meaning to max_body_chars by noting bodies are truncated by default and 0 yields full bodies, complementing the schema's description. It doesn't add much for account or thread_id, but those are self-explanatory.

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 ('Read'), a specific resource ('thread'), and scopes it as 'every message in a thread, in order,' which clearly distinguishes it from singular tools like read_message or search-oriented tools. Even without naming alternatives, the purpose is unmistakable.

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 clearly states the tool is for reading all messages in a thread in order, giving the condition under which it applies. It does not explicitly exclude alternatives or say when not to use it, but the use case is obvious from the description.

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