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

Annotations already declare readOnlyHint=false, openWorldHint=true and destructiveHint=true, so the safety profile is largely carried by structured data. The description adds real value by disclosing that the operation is paid and content-addressed with contract_id = sha256 of the canonical form, implying deterministic/idempotent re-compilation. It does not, however, explain what the destructiveHint covers or what happens if a contract already exists for the same inputs.

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?

A single dense sentence that front-loads the paid/cost warning and the core action before the field breakdown. Every clause carries information; the parenthetical enum list is compact rather than wasteful. Slightly heavy punctuation load but nothing extraneous.

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?

Return values are covered by an existing output schema, so the description needn't explain them, and it correctly focuses on the input contract shape plus the content-addressing behavior that an agent needs to reason about repeat calls. Remaining gaps (terms/parties semantics, closes_at format) are moderate but the tool's core contract is conveyed.

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 0%, so the description must compensate, and it does for two parameters: it defines the settlement rule's four admissible values (above | at_or_above | below | at_or_below), which the schema leaves as a bare string with no enum, and it identifies series_id and strike by name. The optional 'terms' and 'parties' parameters and the format of 'closes_at' (ISO 8601? timezone?) receive no explanation, leaving half the surface undocumented.

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 (compile) and a specific resource (Verified Outcome Contract v0), then enumerates the constituent parts: series, strike, settlement rule, closing time. It is unmistakably distinct from read/settle siblings such as get_contract or settle_contract, though it never explicitly names an alternative.

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?

The only usage signal is the leading 'PAID:' marker, which warns of cost but doesn't say when to compile versus when to fetch (get_contract), settle, or verify. There is no mention of prerequisites such as the series having to exist first, nor any when-not guidance.

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