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

Annotations only declare readOnlyHint/openWorldHint; the description adds the x402 pricing model ($0.004 USDC per call, failed calls free) and the quote-then-sign payment flow, which is essential behavioral context. It also discloses the two-step payment dance and the 'not advice' boundary on the AI read.

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 action and cleanly sectioned (When to use / Use instead / Parameters / Returns). The Returns line largely repeats the field list already given in the opening sentence, which is minor redundancy rather than bloat.

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?

No output schema exists, so the description carries the return shape (articles[] fields plus mood/summary/themes) and does so explicitly. Combined with the payment and routing guidance, an agent has everything needed to call it correctly.

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 four parameters (including the enum and min/max on num) are already documented. The description's parameter lines restate the same defaults and ranges without adding syntax, format, or edge-case detail, 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+resource (get recent crypto news) and immediately scopes it (up to 10 articles from the past hour/day/week), then names the sibling it is not — web_search for non-crypto and crypto_market_pulse for numbers. An agent can distinguish it from all 38 siblings without opening the schema.

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?

Explicit 'When to use' clause plus a 'Use instead' clause routing to web_search and crypto_market_pulse by condition. Nothing about tool selection is left to inference.

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