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

Beyond annotations (idempotentHint=true, destructiveHint=false), the description discloses that the tool costs 1 credit, returns an optimized plan with specific components, and implies a non-mutating operation ('Returns the optimized plan'). This adds useful context without contradicting annotations.

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 compact and front-loaded with purpose. Each sentence adds essential information: what, when, return value, optional parameter, and cost. No filler.

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?

Covers the tool's function, usage context, inputs, outputs, and side effects (credit cost). The description is especially complete given the schema annotations and output schema presence, leaving minimal ambiguity for an agent.

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 already has 100% coverage, but description enhances meaning by stating the plan parameter uses 'Same schema as burnrate_estimate' and explains target_budget's role ('constrain the optimization'). This goes beyond simple field definitions.

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 opens with a specific action and result: 'Get a cheaper equivalent plan by substituting models with lower-cost alternatives.' This clearly distinguishes the tool from siblings like burnrate_estimate and burnrate_track.

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?

Provides explicit usage condition: 'Call after burnrate_estimate if the estimated cost exceeds your budget.' Also gives optional parameter guidance ('Optionally set target_budget to constrain the optimization') and references the predecessor tool.

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