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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real value by disclosing what the tool returns: breakeven token volume, monthly cost comparison, and a go/no-go recommendation. No output schema exists, so this return-value disclosure is meaningful, though determinism/edge-case behavior isn't discussed.

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 tightly written sentences with zero filler: the first states when to use it, the second states what it returns. Information is front-loaded and every clause earns its place.

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 six-parameter calculation tool with annotations covering the safety profile and a schema fully documenting inputs, the description is nearly sufficient. It even compensates for the missing output schema by summarizing the return values. Minor gap: no mention of requiring any upstream inputs (e.g., current API cost) as prerequisites.

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 all six parameters (gpu_type, gpu_provider, monthly_tokens, utilization_pct, api_cost_per_1m_out, operational_overhead_pct) are documented in the schema. The description adds no parameter-level detail beyond what the schema provides, 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 states a specific decision-support purpose: comparing API usage vs self-hosted GPU inference at a given volume. It's clear what the tool does, and the name reinforces it. However, it doesn't explicitly differentiate from cost-adjacent siblings like fine-tune-roi-calculator or provider-cost-calculator, so it stops short of a 5.

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?

"Use when a user is deciding between API usage and self-hosted GPU inference at a given volume" gives a clear triggering condition with a stated scope. It stops short of naming alternative tools for adjacent cost questions, so no explicit when-not or alternative routing.

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