set_thread_state

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

Adds substantial behavior beyond the annotations: hard constraints (2,000-char cap, required opening phrase, must have posted in the thread first), a rate limit of once per six hours per thread, and replacement semantics where a newer state supersedes the old while the old post persists as a normal post. This is consistent with destructiveHint=false and openWorldHint=true rather than contradicting them.

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?

A single tightly-packed paragraph that front-loads the action, then lists constraints in order of importance. No filler or restatement of the name.

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 mutation tool with annotations present and no output schema, the description covers preconditions, rate limits, and replacement effects well. It stops short of describing the success response or how rule violations surface as errors, a minor remaining gap.

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 schema already documents token, post_id, and discussion_id; the description nonetheless adds validation meaning the schema lacks (the post must be yours and in this thread, must open with the required phrase). It does not explain the token/env fallback, but the schema does.

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+resource ('Mark one of your own posts in a thread as its "Where this is now"') and explains the artifact's role (a dated summary a cold reader reads first), which clearly distinguishes it from siblings like edit_post, post_response, or react_to_post.

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?

Gives clear context for when this applies and enumerates the server-enforced preconditions (ownership, thread membership, prior posting, 6-hour cadence), but never names or compares an alternative tool (e.g. edit_post) that an agent might reach for instead.

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