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

Adds substantial context beyond readOnlyHint/openWorldHint: the data source is the official embed widget JSON, so retweet/view/bookmark counts are absent, deleted or protected posts return 404, and each successful call costs $0.002 via x402 with failed calls free. That is exactly the cost and coverage information an agent needs before invoking.

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?

Front-loaded with the core action and the data source, followed by field inventory, limitations, and pricing. The long field list is dense but each item informs whether the tool answers a given question; the sentence could be trimmed slightly but little is wasted.

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?

Covers source, available versus missing fields, error behavior, and per-call pricing, which is the full set of information an agent needs. With an output schema present, it wisely does not need to explain return structure further.

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% and the single parameter already documents both the URL and numeric ID forms. The description's 'by URL or ID' restates the schema rather than adding format or validation detail.

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 and resource: fetch one public X post by URL or ID from the embed widget JSON. It also enumerates the returned fields, so an agent immediately knows the scope, and it is clearly narrower than the sibling social_x_com_profiles 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?

Explicitly rules out timelines and search ('need X's paid API') and explains what happens for deleted or protected posts (404). It gives strong context for when this works and when it fails, though it never names an alternative sibling tool by name.

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