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

Annotations already declare readOnlyHint and openWorldHint, but the description adds real behavioral context beyond them: pagination continuation via after, error semantics (empty/unavailable feeds return not found, throttling is retryable), and the username format constraint. It stops short of describing return shape, but that is a minor gap given the annotations and output schema.

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 tight sentences, front-loaded with the core action and scoping, then operational details, then sibling routing. No redundant restatement of the name or title.

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 read-only listing tool with an output schema present, the description covers scope, parameter defaults, pagination, error behavior, and alternatives. Nothing an agent needs to call it correctly is missing.

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?

With schema coverage at 100%, the baseline is 3, but the description goes further: it states limit defaults to 25 and is capped at 100, explains that after continues a listing, and notes the u/-prefix omission for username. These add meaning the schema fields do not carry.

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 (List) plus resource (public posts submitted by a Reddit username), with the scope qualifier "public" and the input-format note (no u/ prefix). An agent can immediately tell this apart from reddit_user_comments and reddit_post without opening a 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?

Explicitly routes the agent: reddit_user_comments for the user's comments, reddit_post for a single submitted post's details. The alternative conditions are named, leaving little to inference about which sibling to pick.

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