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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior, so the safety profile is covered. The description adds useful behavioral context by specifying what is returned per match (case number, name, date filed, status, city, region), the total match count, and the CA/CB and RC/RD/RM subcategories. It does not discuss pagination or rate limits, but those are partially represented in the schema.

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: purpose first, then returned fields, example queries, and filters. The example questions add functional value for an agent deciding when to use the tool; only a small amount of redundancy with schema descriptions keeps it from a 5.

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?

For a read-only search tool with no output schema, it covers the important semantic ground: what counts as a search, what each result contains, and what filters exist. It does not mention error behavior, pagination defaults, or sibling-tool routing, but the schema carries pagination details and the examples cover typical calls.

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?

Input schema coverage is 100%, so the baseline is 3; the schema already documents all 9 parameters with descriptions. The description adds some interpretive value—mapping query to employer/union/case-number and expanding C/R into CA/CB/RC/RD/RM—but most parameter behavior is already in 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 description opens with a specific verb and resource ('Search US National Labor Relations Board cases') and clearly scopes by employer, union, or case number, then enumerates returned fields and filters. It is unambiguous about what the tool does, but it never explicitly names or contrasts siblings like nlrb_case or nlrb_recent_filings, so sibling differentiation is implicit rather than explicit.

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 provides concrete query examples like 'is Starbucks facing an NLRB charge' and 'union election petitions at Trader Joe's', and states available filters, giving clear context for when to invoke a case-search tool. It stops short of explicit when-not-to-use guidance or named alternatives, so it does not earn a 5.

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