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

Annotations already declare readOnlyHint=true and idempotentHint=true, but the description adds crucial behavioral details beyond those: the requirement for at least one filter, the owner-PII redaction condition, and the pagination mechanism (totalCount, nextOffset, offset). These are non-obvious behaviors that would otherwise be unknown. No contradiction with annotations exists.

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 three sentences with zero filler. It leads with the core purpose, then covers the required-filter constraint and the redaction caveat, and finishes with pagination behavior. Every sentence contributes essential information, and the structure is logical — purpose first, then constraints, then continuation mechanics.

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 tool with 7 optional parameters, an output schema, and a pagination design, the description covers all critical operational aspects: search fields, output format, mandatory-filter condition, deployment-specific redaction, and pagination flow. It even names the follow-up tool (faa_lookup_registration). There is no missing information an agent would need to invoke it correctly, especially given the annotations already cover read-only idempotency.

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 coverage is 100% with individual parameter descriptions, providing a baseline of 3. The description adds meaningful context on top: it clarifies that at least one filter is required (a cross-parameter constraint not in the JSON Schema, since no property is marked required), and it explains how offset relates to pagination via nextOffset. It also reinforces the ownerName rejection condition, tying the parameter to the deployment context. This goes beyond mere parameter listing.

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 active US civil aircraft registrations' and lists the searchable fields. It clearly distinguishes itself from the sibling tools by mentioning the drill-in step to faa_lookup_registration, establishing it as the search entry point rather than a lookup. The output expectation ('decoded summaries with N-numbers') is also stated, leaving no ambiguity about the tool's role.

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 explicitly states a hard requirement ('At least one filter is required') and provides conditional guidance for when owner-name search is unavailable ('search by make/model, state, aircraft type, or Mode S code instead'). It also gives precise pagination instructions, telling the agent to pass nextOffset back as offset. This is actionable, context-specific guidance that distinguishes when and how to use the tool.

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