get_thread

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

No annotations exist, so the description carries the whole burden and mostly delivers: it discloses that matching is subject-based plus header-linked, that results are ordered oldest first, that bodies are capped at the 30 most recent with quoted lines stripped, and it flags content as untrusted third-party data (a real prompt-injection warning). It does not say what happens when no thread is found, nor anything about cost or result shape.

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?

Front-loaded with purpose, then candidate-finding, then body behavior, then the safety note — four sentences that each add distinct information with no filler. The mechanism detail is dense but load-bearing rather than decorative.

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 5-parameter tool with no annotations and no output schema, the description covers the behaviors an agent most needs to avoid misuse. The remaining gap is the return value: with no output schema, it should say roughly what a reconstruction yields (message list, per-message fields) and what a no-match result looks like.

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 0%, so the description must compensate, and it only partly does: `folder` and `also_folders` get real meaning (subject matching, Sent folder example) and `include_bodies` gets both its effect and the 30-message cap. `uid` is only implied and `max_chars_per_message` is never mentioned at all, leaving a meaningful gap.

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 ("Reconstruct the conversation a message belongs to") and nails the scope with the mechanism (Message-ID / In-Reply-To / References) and ordering ("oldest first"). That is enough to separate it from get_message (single message) and search_messages (query-based lookup) without opening any schema.

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?

Explains the selection logic an agent needs operationally: candidates are located by subject in `folder` plus `also_folders`, with the concrete hint "(e.g. the Sent folder)" so the caller knows why the extra folder matters. It stops short of an explicit use-this-instead-of-get_message rule or a when-not-to-use caveat.

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