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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. Beyond that, the description discloses a specific behavioral trait—Reddit CDN URLs are filtered out, so only genuinely external links are returned—which is not present in the annotations and is valuable for setting expectations.

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 sentences with no filler. The core action is front-loaded, the filtering caveat follows immediately, and the use cases are compactly attached. Every word earns its place.

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, link-extraction tool, the description along with annotations and full schema coverage is nearly complete. The only minor gap is the lack of an explicit output shape (e.g., whether URLs are deduplicated or accompanied by post context), but the return type is strongly implied by 'Extract all external URLs'.

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 all five parameters (query, label, limit, subreddit, include_reddit_links) are already documented. The description adds no additional parameter-level meaning beyond the schema, which aligns with the baseline 3 for full schema coverage.

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?

The description uses a specific verb ('Extract'), a resource ('external URLs from saved posts'), and a matching criterion ('matching a query'). It clearly distinguishes itself from siblings like search_posts or get_recent by targeting link extraction rather than post retrieval, and adds the differentiating detail of filtering out Reddit CDN URLs.

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?

Two concrete use cases are provided ('compile all resources about X', 'get all links from my saves about Y'), which clearly signal when to invoke this tool. It does not explicitly name alternatives or state when not to use it, but the context is clear enough for an agent to select it over post-search siblings.

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