Post a thread

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

Annotations indicate readOnlyHint=false and destructiveHint=false, but the description wisely adds a critical behavioral note: 'Real account — use sparingly; server enforces minimum gap to avoid rate-limit/automation flags.' This goes beyond what annotations provide and helps the agent avoid misuse. No contradiction with annotations.

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 description is two concise sentences with an emoji warning. It front-loads the core purpose and then adds the critical rate-limit caution. No extraneous words.

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 the core purpose and a key behavioral warning, but omits details about return values (since there is no output schema). It also does not orient the agent among numerous sibling tools. Given the schema coverage of parameters, it is adequate but not 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 description coverage is 100%, so the schema already explains all parameters (text, chain, media). The description mentions 'text and/or media (images & video)' but does not add meaningful detail beyond the schema. Baseline score of 3 is appropriate.

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 clearly states the action ('Post'), the resource ('a new thread'), and the target ('YOUR Threads account'). It specifies content types (text and/or media), distinguishing it from sibling tools like 'reply_to_thread' or 'quote_thread' which modify existing threads.

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 implied through the purpose statement, but there is no explicit guidance on when to use this tool versus alternatives (e.g., when to use 'reply_to_thread' instead). The warning about sparing use provides behavioral context but does not compare to siblings.

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