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

Goes well beyond the readOnly/openWorld annotations: discloses duplicate removal, result ordering (first-input order), that missing ids are reported back, the batching behavior (max two upstream requests of 500 ids), the 8 MiB response cap failure mode, and the credit pricing formula with min/max. That is exactly the operational context annotations cannot express.

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?

Four dense sentences, front-loaded with what the tool does before the caveats, then cost, then the sibling routing. Every clause carries a fact an agent would otherwise have to discover by trial (dedup, ordering, cap, credits).

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?

An output schema exists, so return shape needn't be described, yet the description still covers the non-obvious result semantics (missing ids listed, input ordering preserved) and the cost/limit envelope. Nothing needed to call it correctly is absent.

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% and already documents the comma-separated format and 1,000-id ceiling, so the description needn't restate syntax. It does add meaning the schema omits: duplicate ids are collapsed and output preserves first-input order, which shapes how the caller should assemble the id string. A 4 rather than 3 for that genuine increment.

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 and resource ('look up ... Reddit comment ids in Arctic Shift's public historical archive') with explicit scope (up to 1,000 ids, archived comments only). It also distinguishes itself from the two nearest siblings, naming reddit_archive_comments_search for id discovery and reddit_archive_posts_ids for posts.

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: use reddit_archive_comments_search to discover ids, this tool to resolve known ids, and reddit_archive_posts_ids for posts. It also gives a concrete recovery procedure (split oversized id sets and retry) for the failure mode it names.

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