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

Annotations already mark the tool read-only/idempotent/non-destructive, and the description adds valuable behavioral context: numeric breakdown when an authoritative rule exists, qualitative feeNotes with a source URL for PDF-only sources, and a strict no-fabrication policy. This goes well beyond the structured 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?

Three short sentences with no filler: purpose and inputs, return-mode behavior, and anti-fabrication guarantee. The most important information is front-loaded.

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?

With full schema documentation and an output schema present, the description covers the key additional context: when numeric vs qualitative output occurs and the policy not to invent amounts. Nothing an agent needs to invoke it 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?

The input schema already documents all three parameters at 100% coverage, so the description does not need to repeat them. It merely names jurisdiction, project type, and valuation without adding meaning beyond the schema.

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 first sentence names a specific verb ('estimate'), a clear resource ('permit fee'), and the exact input basis ('jurisdiction, project type, and project valuation'). This distinguishes it from siblings like check_permit_requirements and answer_permit_question.

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 clearly states this is for residential projects and requires jurisdiction, project type, and valuation. It also explains the fallback condition when cities publish fees as PDFs/spreadsheets, though it does not explicitly name alternatives or exclusions such as commercial projects.

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