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

Annotations already provide readOnlyHint=true, and the description reinforces this with 'read-only.' It adds substantial extra context: '1 credit' cost, 'Reddit comments via RSS are flat/unscored,' and the account requirement. This goes well beyond the minimal annotation.

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 compact and information-dense: purpose, parameter clarifications, cost, read-only, RSS caveat, and account requirement all fit in three sentences with no waste.

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?

Given the tool's simplicity and the absence of an output schema, the description covers purpose, parameters, cost, read-only nature, and comment behavior. It doesn't detail the exact return structure, but the phrase 'with its comment thread' suffices for a fetch-one tool. A slightly more explicit mention of when to use this vs. listing tools would push it to 5.

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?

The schema has descriptions for id and platform only, while commentLimit and includeComments lack schema descriptions. The description compensates by explaining id formats (permalink URL, t3_xxx, bare id, HN numeric) and clarifying includeComments default and commentLimit ≤ 20. This adds meaning beyond 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?

Description opens with 'Fetch one post/story with its comment thread,' a specific verb and resource. It clearly distinguishes from siblings like social_list_posts (listing multiple posts) and social_get_user (user data).

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 tool is clearly intended for retrieving a single post/story by ID, but it does not explicitly name alternatives or state exclusions. It does give context on when to use it (you have a post ID) and provides a prerequisite about the Prowlo account.

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