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

Annotations only declare readOnlyHint and openWorldHint. The description goes well beyond them by enumerating the payload (terms, status history, settling index, venue, sources), flagging a negative result boundary (no index values), and disclosing the commercial constraint: 50 free calls per day then $0.01 USDC on Base per call via x402, which is decisive for an agent's call budgeting.

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?

Four short sentences: usage trigger first, then return contents, then the exclusion, then cost. No filler, and the most decision-relevant information is front-loaded.

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?

There is no output schema, so the description must carry the return shape, and it does by listing the returned components and noting the one thing omitted (index values). Combined with the rate-limit/payment note, an agent has everything needed to call it and interpret the result.

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% and the single 'contract' parameter already documents accepted forms (ct- id, exchange code, full name) with an example. The description adds no identifier-format detail beyond that, 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?

The description names a specific verb and resource ('need one compute derivative contract in full') and states what is returned, which tells an agent this is a single-record lookup rather than a search or list. It stops short of naming the sibling lookups (search_compute_contracts, get_compute_record), so the boundary is implied by 'one ... in full' rather than made explicit.

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?

'Use when you need one compute derivative contract in full' gives a clear trigger condition, and 'Index values are not returned' sets a scope expectation. However, it never says which alternative to use when the id is unknown (e.g. search_compute_contracts) or how this differs from get_compute_record, leaving routing to inference.

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