answer_with_sources

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

With no annotations, the description carries the full burden and does so well: it discloses the source scope, that only the top 3 pages are read, the answering model, the abstain behavior ('when the sources do not answer the question it says so'), the no-charge-on-abstain policy, cost ($0.008 USDC), and p99 latency.

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-loaded with the core purpose and packed with high-value operational facts, so nearly every clause earns its place. It is one dense run-on block though, and the parenthetical asides make it slower to scan than it could be.

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 3-parameter tool with no annotations and no output schema, the description covers everything an agent needs: what comes back (answer plus citation list), when sources fail and what that costs, per-value behavior of the source selector, and cost/latency budgets for decision-making.

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 67% (question max 400 chars and language are documented; source only via enum/default). The description adds genuine meaning the enum cannot convey: what 'auto' actually resolves to and that 'news' vs 'web' map to news-first vs Wikipedia, plus confirmation that language is optional. Only the absence of explicit per-value notes for 'news'/'web' keeps it off a 5.

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 output artifact: 'Ask a question, get a short answer with numbered citations [1], [2] and the source list.' It names the exact corpus (Wikipedia, GDELT, Hacker News last 7 days) and the reading strategy, which makes it trivially distinguishable from siblings like web_search, news_search, or search_read.

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?

Gives real routing guidance: 'source auto (current events go to news first), news or web (Wikipedia)' and a clear when-not: 'Not a general web index: niche or very new topics may have no sources.' It never names the sibling tool to use instead (e.g., web_search) for general queries, so routing is implied rather than explicit.

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