create_thread

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

Annotations only declare openWorldHint=true, so the description carries the burden and does well: it discloses partial-failure semantics ('stops at the first failure and reports what was posted') and billing behavior ('billed like create_post'). It does not cover authorization requirements or rate limits, but the failure/billing disclosure is genuinely valuable.

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 short sentences, front-loaded with the core action, followed by failure behavior and billing. No filler, and each sentence conveys a distinct fact.

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 mutating tool with no output schema and a nested posts array (1-25 items), the description supplies the sequencing rule, the stop-on-failure contract, and the cost model. The remaining gap is that it says what was posted is reported but gives no shape of that report.

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 67% and already documents account and reply_to_post_id. The description adds the key missing semantic for the posts array: it is ordered, with each entry replying to the prior one. That ordering/chaining meaning is not derivable from the schema alone.

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?

It states a specific verb and resource (publish a thread) and immediately clarifies the semantics: each post replies to the previous one. This implicitly separates it from create_post, but it never names the sibling, so the differentiation is inferential rather than explicit.

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: an agent can infer this is for multi-post chained publishing rather than a single post. There is no explicit when-to-use/when-not guidance or a pointer to create_post as the alternative for a single post.

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