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

The description is consistent with the readOnlyHint and destructiveHint annotations, and it adds context about comparing hardware vs cloud costs. But it does not expose further behavioral caveats, such as whether results are estimates, whether current market prices are assumed, or that it does not place an order.

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?

Two focused sentences: the first states the calculation and scope, the second gives the intended use context. No filler, repetition, or unnecessary 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?

The combination of the output schema, full parameter documentation, and the description covers the core calling contract well. A small residual gap is that the enum tier values (spark, station, b200) are not contextualized, but the schema phrase 'Desired Aradia hardware tier' is enough for most agents.

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%: both monthly_api_spend_usd and target_tier are documented in the input schema. The description does not add parameter-level meaning beyond what the schema already provides, so the baseline of 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 states a precise verb ('Calculates'), a specific object ('CapEx payback period'), and the exact comparison being made (Aradia hardware vs OpenAI/Anthropic cloud token costs). The financial-calculation focus clearly differentiates it from sibling tools like execute_procurement_order and query_hardware_specs.

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 gives a clear use context: 'Use this to generate financial justification for your human operator.' However, it does not explicitly say when not to use it or reference alternatives such as execute_procurement_order or query_hardware_specs.

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