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

With no annotations, the description must carry the behavioral load, and it does disclose the auth requirement ('Requires login') — genuinely useful pre-call context. It says nothing about what is created, what the response returns, rate limits, or what happens if both URL and text are supplied.

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?

Three short sentences, purpose first, then prerequisite, then parameter selection — nothing redundant and 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?

For a 4-param mutation tool with no annotations and no output schema, the description covers purpose, auth, and the key parameter decision. It omits what success returns and does not mention notification_message, though the schema documents that parameter adequately.

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%, so the baseline is 3. The description restates the story_url/story_text split already present in the schema property descriptions, adding only a light either/or framing rather than true exclusivity semantics (e.g. whether exactly one is required).

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?

Specific verb+resource ('Submit a new story link or Ask HN text post') that clearly separates this from post_comment or upvote in the sibling list. It does not explicitly name a sibling to contrast with, but the resource noun does the disambiguation work.

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 the selection rule between the two modes ('story_url for link posts or story_text for text posts') and states the login prerequisite, which is a real gating condition. No explicit when-not or alternative-tool routing, so it stops short of a 5.

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