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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), so the bar is lower; the description still adds genuine context by disclosing cost/auth ('Free, no key'), validator parity with the backtest queue, and the default time window. It omits what happens on validation failure and whether pricing is a simulation or a commitment.

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?

Three sentences, front-loaded with the core action, and every clause carries information an agent needs (validator parity, cost, date-argument rules, default). No filler or restatement of the name.

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 should carry return-value expectations. It says it 'validates' and 'prices' but never states what comes back (validation errors vs. a price figure), nor what the response looks like when a strategy fails validation — a meaningful gap for a tool whose primary job is validation.

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 67%, so the schema documents most fields, but the description adds meaning the schema lacks: the from/to-vs-days mutual exclusivity, the 7-day default, and that files are 'sent as contents'. venue and assets get no added semantic color, but their enum/example descriptions in the schema are adequate.

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 two specific verbs (validate, price) and the exact resources (manifest.json + source files, contents-based), plus the scope qualifier. The phrase 'the exact validator the backtest queue runs' is a concrete distinguishing detail. It does not, however, explicitly differentiate itself from siblings like backtest_quote, and 'price it' overlaps with that sibling's apparent domain.

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?

Gives real invocation guidance: 'Free, no key' removes auth uncertainty, 'Give either from/to or days' defines a mutually exclusive parameter choice, and the default fallback (most recent 7 days) is spelled out. No explicit when-not-to-use or named alternative (e.g. backtest_quote for pure pricing) is offered.

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