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

With no annotations, the description carries the burden and does well: it discloses cost ('FREE'), side-effect freedom ('no wallet or document upload'), and non-inspection ('does not inspect or validate'). It doesn't explicitly state that it returns a quote or price, but the name and purpose strongly imply it.

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 tight sentences, each earning its place: one for pricing/inputs, one for when to call, one for what it doesn't do. The 'FREE' qualifier is front-loaded, and there is zero redundant content.

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 output schema exists, so return values need no explanation. The description covers prerequisites (none), cost, side effects, and invocation timing. Minor gap: it doesn't explain whether page_count applies only to PDF or also to other document types, though the phrase 'PDF page count' implies it.

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 0%, so the description must compensate. It adds useful context by mapping 'PDF page count' to page_count (limiting it to PDFs) and calling file_size_bytes 'optional.' It doesn't clarify enum meanings for document_type or range behaviors, but the schema already provides those constraints.

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 clearly states a specific job: quote the lowest-priced Invoice Preflight tool based on document type, page count, and byte size. It explicitly distinguishes itself from actual preflight work with 'It does not inspect or validate the document,' preventing confusion with the sibling preflight tools.

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?

It gives an explicit trigger condition: 'Call this before a paid invoice tool when the tier is uncertain.' It also states this is free and requires no wallet/upload, which clarifies it is a safe preliminary step. It doesn't name sibling alternatives directly, but the intent to route before paid tools is clear.

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