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

Annotations already cover read-only, idempotent, non-destructive and closed-world, so the description wisely spends its words elsewhere: it discloses the coverage limit (only boards with readable public feeds, a few dozen at most), result ordering, and a prompt-injection warning that titles are untrusted text. It doesn't discuss pagination or how `limit` interacts with the cap.

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 with the core result definition first, then filters, then the trust warning. Every sentence carries information that isn't duplicated from structured fields.

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?

No output schema exists, but the description compensates by enumerating the returned fields (board, time, link) and the ordering. Coverage ceiling is disclosed. Only minor gaps remain: how `limit` behaves at the upper bound and whether results are truncated silently.

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 100% schema description coverage, the schema already documents all four parameters. The description reinforces the intent of `board`, `q` and `since` in prose but adds no format or behavioral detail beyond the schema, and never mentions the `limit` cap, so the baseline 3 applies.

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 resource and shape: newest post titles from readable boards, newest first, each with board, time and a link back. This is unmistakably distinct from every sibling (check_reply, find_site, list_directory) without needing to open 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?

It makes clear when the tool applies (recent posts across boards) and lists the three narrowing filters plus the `since` cutoff, giving clear usage context. It does not name an alternative tool or state when not to use it, 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.