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

Annotations already declare readOnlyHint, openWorldHint and idempotentHint, so the safety profile is covered by structured data. The description adds value beyond that by enumerating what the response actually contains, which matters because there is no output schema. It does not mention failure modes such as deleted, private or rate-limited posts, which keeps it short of a 5.

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 sentences, zero filler. The return contents are front-loaded and the sibling routing is compressed into a single clause, so every sentence earns its place.

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 single-parameter read tool with no output schema, the description covers both what is returned and which sibling to use instead, which is the essential information. It stops short of describing error behavior for inaccessible posts, a minor but real gap for an open-world fetch.

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?

There is one parameter, `url`, and the schema already documents it at 100% coverage, including the accepted link format and the numeric-ID alternative. The description adds no additional meaning about the parameter, so the baseline of 3 applies rather than a higher score.

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 ("Returns a single X (Twitter) post") and immediately pins down the output shape: Markdown with author, date, text, quoted post, image links and counts. That level of specificity distinguishes it from read_x_article and the video tools without requiring the agent to open any schema.

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?

Names two concrete alternatives and the exact condition that selects each: use read_x_article "for an Article" and get_x_video_transcript "for a video's words." This is explicit when-to-use-else routing rather than implied guidance, leaving little for the agent to infer.

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