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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable context: it is prep-only, has zero cost (0 IU), and does not interact with the sealed engine or exercise any capability class beyond input-shape convention.

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?

The description is longer than strictly necessary, but it is well-structured with clear sections (Purpose, Use when, Do not use when, Capability class, Path fit, Cost). The front-loaded first sentence carries the core meaning, and each subsequent section provides non-redundant useful context.

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?

Given the tool's moderate complexity (2 params, output schema, annotations), the description goes beyond minimum requirements by explaining the tool's role in the broader workflow (validation via MCP vs. production attestation), cost implications, and exact exclusions (no scoring). It is complete and self-sufficient.

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%, with clear descriptions for bid_px and ask_px. The description does not add parameter-level syntax but provides semantic context on how the arrays relate to the tensor convention (e.g., level 1 first, bid/ask levels), which is marginal added value over the schema.

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 states a specific verb ('Render') and resource ('L2 order-book snapshot into the 20×20 complex128 thermometer tensor') and explicitly notes that it does NOT invoke the sealed engine. This clearly distinguishes it from sibling scoring tools like kirk_score_book.

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 description provides explicit 'Use when' scenarios (sanity-checking bid/ask level convention, inspecting cell patterns, debugging entropy values) and a 'Do not use when' clause naming kirk_score_book as the alternative for scoring. This is exemplary guidance.

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