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: it discloses the x402 price ($0.01 USDC on Base), that billing occurs only on a 200, and the failure modes (404 unknown id, 400 invalid args, 503 during data refresh) with the guarantee that 404/400 fire before payment. That is exactly the behavioral context an agent needs before calling a paid endpoint.

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 what the card contains, then usage, then error/pricing semantics. Minor redundancy: the pay-only-on-success rule appears twice ('charged only for a 200' and 'charged only for a successful answer'), and the price sentence partly repeats itself.

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 or annotations exist, and the description compensates fully: it enumerates return contents, the id provenance, error codes, and payment semantics. An agent has everything needed to decide, prepare arguments, and interpret failures.

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 100%, so the baseline is 3; the description adds value beyond the schema by naming the MCP-side source for the required id (search_opportunities), which the schema only describes in terms of the raw HTTP route. Capital and duration are left entirely to the schema, so not 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 resource ('Full risk card for one Base yield opportunity') and enumerates the payload: risk score, yield sources, sustainable APY, liquidity, dependencies, recent risk events. It does not explicitly contrast with the closest sibling, get_opportunity_score, so an agent must infer which returns the full card versus the score alone.

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?

'Useful before depositing into, recommending or comparing a Base yield' gives clear call contexts, and 'In this MCP server, ids come from search_opportunities' routes the agent to the correct upstream tool for the required id. No explicit when-not-use or exclusions against score/graph siblings, which keeps it below a 5.

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