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

Goes well beyond the readOnly/openWorld annotations: discloses merge and dedupe policy, newest-first ordering, returned fields and per-engine status, the no-full-text limitation, that Google links are redirects, ~15 s latency with a 45 s timeout recommendation, and x402 pricing where failed calls are free. Latency, cost and data-fidelity caveats are exactly the operational context annotations cannot carry.

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?

Front-loads the core capability and sources before the caveats, and every sentence carries operational weight (latency, cost, return shape, alternatives). It runs as one dense paragraph, which makes the sibling-routing and pricing clauses easy to skim past, but there is little genuine filler.

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 multi-source aggregator with a paid, slow call and an output schema already documenting return structure, the description supplies everything else an agent needs: source list, dedupe semantics, latency budget, cost model and sibling routing. Nothing material is left for the agent to guess.

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 the schema already documents q, limit and engines including defaults and ranges. The description reinforces engine selection ('merged, de-duplicated') but adds no syntax or edge-case detail beyond what the schema states, 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 verb and resource ('Search news across the web') and immediately names the three underlying sources (Google News RSS, Bing News RSS, GDELT Context 2.0), plus the merge/dedupe/sort behavior that defines the result. It also names overlapping siblings and the distinct need each serves, so the agent can separate this from search_google_news or search_gdelt_news.

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 away from two siblings ('search_bbc_news_articles when you need BBC News top stories...', 'search_gcaptain_maritime_news when you need gCaptain maritime news'), which is real when-to-use guidance. It stops short of saying when to pick this aggregator over the narrower single-source siblings like search_google_news or search_gdelt_news, so the cross-source case is implied rather than stated.

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