x_reply_post

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

Annotations already establish this is a non-read-only, non-destructive write. The description adds the auth/config requirement (mode and scope), which is genuine value beyond the annotations. It omits rate limits, whether the reply threads to the parent, and error/permission failure behavior.

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?

Two tight sentences with zero filler; the action is front-loaded and the prerequisite follows. Sized appropriately for a simple two-parameter tool.

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?

No output schema exists, so the description should say what comes back, and it doesn't. Combined with undocumented parameters and no sibling differentiation, the definition is adequate but leaves real gaps for a write tool.

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?

Two required parameters with 0% schema description coverage, so the schema alone explains nothing about 'text' (reply body) or 'postId' (target post). The description mentions replying to 'a post' but does not map either parameter or note the 25000-char limit implied by the schema.

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?

Names a specific verb+resource ('Reply to an X post'), which is unambiguous on its own. It does not differentiate from the closely related sibling x_create_post (a reply is a kind of post creation), leaving the agent to infer the boundary.

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 a real precondition (X_MCP_MODE=read-write and tweet.write scope), which is useful operational guidance. It says nothing about when to prefer this over x_create_post or x_get_post, and no exclusions are stated, so usage is only partially covered.

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