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

The description adds a genuinely useful behavioral fact the annotations do not carry: the cost of $0.03 USDC per call. Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered; however, nothing is said about output shape, accuracy/confidence, or failure behavior on malformed input.

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?

A single front-loaded sentence pairing the operation with its input sources; the pricing parenthetical is compact. Nothing is wasted, though the line is doing very little work overall.

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 no output schema, no parameter documentation, and no usage guidance, this definition leaves the agent guessing about what the return value looks like (key-value object? JSON?) and how to shape the `fields` argument. A structured-extraction tool needs more than one line to be callable with confidence.

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% and the description does not explain either parameter. In particular, the role of the optional `fields` array (a list of field names to extract?) is left entirely ambiguous, and the expected format of `text` is unstated, so the description fails to compensate for the coverage gap.

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 operation and resource: structured field extraction producing key-value pairs from emails, forms, and documents. It is clearly distinguishable from siblings like summarize, classify, and sentiment, though it does not name any sibling explicitly.

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?

There is no statement of when to use this tool versus alternatives such as summarize or classify, no prerequisites, and no exclusions or input-type limits. Usage must be inferred entirely from the one-line purpose.

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