x_post_create

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

Annotations already mark this as non-read-only and non-destructive; the description adds useful behavioral context beyond that, including the return value (id + URL), the per-post cost implication of URLs, and the read-only policy guardrail. 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 a single front-loaded sentence that states the platform, action, key parameter shape, and return value. The trailing cost and policy notes are important and non-redundant, and there is no filler.

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 tool has a complex schema with nested poll objects, media constraints, and enums, but the schema fully documents those details. The description covers the high-level feature set, return value, cost behavior, and policy gate, making the tool adequately described for correct invocation.

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?

Input schema coverage is 100%, so the schema already documents all parameters, constraints, and mutual exclusions. The description's parameter list is a helpful summary but adds no new semantic meaning; even the URL cost note is repeated in the text property's schema description.

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 states a specific verb and resource: 'create a post' on X/Twitter, and lists the supported optional fields. It is immediately distinguishable from siblings like x_post_get, x_post_delete, and x_post_hide_reply because it is the only creation tool.

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?

The description clearly anchors the tool's purpose to creating posts and adds a policy constraint: it is disabled under a read-only policy. It does not explicitly name alternatives, but none of the sibling tools perform post creation, so the usage context is unambiguous.

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