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

Without annotations, the description carries the full burden: it does disclose the auth requirement (session cookie from login), which is real behavioral context beyond the schema. But it omits mutation-relevant traits such as idempotency (already-upvoted items), failure modes, rate limits, and whether the action can be undone.

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 short sentences, zero waste, with the core action front-loaded and the prerequisite following. Nothing could be removed without losing information.

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 an unannotated mutation tool with no output schema, the description covers the action and auth prerequisite but says nothing about the response, idempotency, or error behavior when voting fails or the cookie is invalid. Adequate minimum, but leaves real gaps an agent would want filled.

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 description coverage is 100%, so both parameters are already documented, establishing a baseline of 3. The description adds only that item_id may refer to either a story or a comment, a mild clarification beyond the schema text.

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 ('Upvote') and resource ('a story or comment by item id'), and the resource scope distinguishes it from read siblings like get_item and browse_feed. An agent can tell immediately what this does without opening the 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?

The prerequisite 'Requires a valid hn_session_cookie from login' implies the login sibling must be called first, which is useful routing. However, there is no guidance on when not to use it, no mention of what happens if already voted, and no exclusions relative to other write tools.

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