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

Annotations already cover read-only, idempotent, non-destructive, open-world behavior, so the description rightly focuses on data semantics instead. It adds genuine context beyond annotations: submitted quantity can differ from the configured template size, sizing carries the exchange step and minimums the size was snapped to, and created_ms is absent rather than zero for older orders.

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 first sentence front-loads the resource, scope, and ordering, and each later sentence targets a distinct semantic subtlety. It is dense but mostly earns its place, though the quantity/sizing explanation is fairly long for what is largely return-value detail.

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?

For a simple three-parameter read tool with full schema coverage and an output schema, the description covers the important ambiguities around order quantity and missing timestamps. It leaves minor gaps such as whether partially filled orders are included and whether limit truncation is signaled, but nothing critical is missing for correct invocation.

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 side, limit, and runtime_id are already documented, including the enum and the runtime_id pattern. The description only restates that results can be filtered to one side and adds no new syntax, defaults, or edge-case meaning for the inputs, 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 (open BUY and SELL orders on one runtime's ladder) and adds scope plus ordering (highest price first, optionally filtered to one side). It is clearly distinguishable from siblings like list_history, list_audit, and list_runtimes without opening any schema.

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 phrase 'one runtime's ladder' implies you need a runtime id, and the schema points to spotgrid.list_runtimes for that. But there is no explicit when-to-use versus when-not guidance and no named alternative for retrieving filled or historical orders, so the agent must infer the boundary with list_history.

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