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

Goes well past the readOnlyHint/openWorldHint annotations: 5-minute feed caching, degradation behavior ('a feed that fails is listed in unavailable'), and the full payment contract ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failures not charged). For a paid, networked read tool this is exactly the behavioral context an agent needs.

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?

Content is front-loaded (sources -> fields -> filtering -> caching -> pricing) with no filler sentences. It is delivered as one dense run-on string, which slightly hurts scannability but wastes nothing.

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?

Given a paid, multi-source scraper with an output schema present, the description covers the source set, return fields, filtering, caching/failure semantics, and cost model. Nothing an agent needs to decide or invoke correctly is missing; return-value detail is correctly left to the output schema.

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 all three parameters; baseline is 3. The description restates the q and coin filters and the 200-char summary cap but adds no syntax, format, or edge-case detail beyond the schema, and omits limit entirely.

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 (latest crypto headlines) and enumerates the exact upstream sources (CoinDesk, Cointelegraph, Decrypt, The Block, Bitcoin Magazine), so an agent can distinguish it from general-headline siblings like text_headlines or feed without opening the schema. It also defines the returned shape up front.

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 clear context for use ('Filter by words in the text (q) or by coin') and draws a scope boundary ('Headlines and links only, not the articles'), which tells the agent when this tool is insufficient. It stops short of naming an alternative tool for full-article text or non-crypto news, so no explicit exclusions/routing.

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