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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description goes further by disclosing the computation itself (Section 45F at 40%/500k, or 50%/600k for an eligible small business), the 2026 7,500 USD dependent care limit comparison, and the disclaimer 'Educational estimate, not tax advice' — meaningful expectations about output nature and limits.

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?

Dense but front-loaded: the comparison and its three arms come first, followed by the cost/credit outputs, then the input rules and disclaimer. No filler sentences; every clause conveys new information.

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?

An output schema exists and annotations cover safety, so the description's remaining obligations are met: geography restriction (TX/NY), required input semantics, defaults, credit assumptions, and an explicit non-advice disclaimer. Nothing an agent needs to invoke this correctly is missing.

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 the baseline is 3. The description adds real value beyond the schema by spelling out the smallBusiness credit math (higher rate and cap) and by describing worksiteZip/state as alternative locators and annualPrices as replacing area defaults — semantics that clarify when each parameter matters.

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?

States a specific verb and resource ('Compare three ways to give staff child care places') and enumerates the three options: reserved places at providers, shared center, and on-site center. It also scopes the inputs precisely (one number of staff children under 5, Texas or New York), so an agent can tell immediately this is a cost-modeling tool, distinct from the scan/submit siblings.

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?

Gives concrete input guidance: 'Pass worksiteZip or state, and annualPrices from real quotes when known,' which resolves the ZIP-vs-state choice and tells the agent when to override defaults. However, it never says when not to use this tool or how it relates to the sibling scan_childcare_slots beyond the schema note, so the guidance is clear but not exhaustive.

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