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

Goes well beyond the readOnly/idempotent annotations: discloses the 6-calls-per-minute rate limit, that it is free with no key and nothing stored, the exact evaluation semantics (bar-close rules, per-schedule fills, in-bar stops, non-loosening trailing stop, no look-ahead), fee/slippage/funding accounting, the 5000-bar cap, and that returns are never annualised.

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?

Long, but front-loaded with the endpoint, cost, and rate limit, and each subsequent sentence carries behavioral weight. It is dense rather than padded, though the return-field enumeration could be tightened.

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?

With no output schema and nested spec objects, the description must carry the return-shape burden, and it does: it enumerates card.summary fields, cost_to_edge, size_sweep, edge_gone_at_usd, window, and per-trade list. Nothing an agent needs to call or interpret it is missing.

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 days, spec, sizes, and nav_usd. The description adds some framing (last N days, size table from the spec, nav_weight/risk_per_stop sizing) but no syntax or format detail beyond the schema, so the baseline 3 is appropriate.

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 concrete verb+resource (run an execution spec over real bars, get its paper report card) and names the endpoint. It explicitly positions itself against the sibling strategy_spec_validate by sharing the same validation errors, so an agent can tell it apart without opening schemas.

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?

Usage is implied by the rich description of what paper-testing does, and the reference to strategy_spec_validate hints at the relationship, but there is no explicit when-to-use/when-not guidance or named alternative with a selection condition. The agent must infer that this is the simulate-to-see-costs option.

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