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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond that: results are sorted by sufficiency rating ascending, the dataset covers 621,000+ bridges, no auth is required, and the source is public-domain USDOT/FHWA data. This goes beyond what structured annotations alone convey.

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 front-loaded with the core purpose, followed by sort behavior, returned fields, use cases, and data/auth notes. It is slightly longer than necessary — the field list and 'useful for' sentence are somewhat redundant with schema/output schema and generic context — but every section earns its place and no irrelevant detail is present.

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?

Given the full schema coverage, rich annotations, and presence of an output schema, the description is largely complete. It covers the query geometry, radius constraint, sort order, returned fields, data scale, and authentication posture. Minor omissions like pagination or no-results behavior are not critical for this tool's complexity and are likely covered by the output schema.

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 100%, so the baseline is 3. The description restates the 50-mile radius limit and mentions sort order, which overlaps with schema descriptions, but does not add meaningful new parameter-level meaning beyond that. It does not compensate for anything missing because the schema already documents all four parameters thoroughly.

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 action and resource: 'Find US highway bridges within a specified radius (up to 50 miles) of a latitude/longitude coordinate.' It clearly distinguishes this from general NBI search by emphasizing the geospatial radius, and the explicit reference to nbi.search and the field list helps an agent map it against sibling 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?

The description clearly establishes the context for use — proximity-based bridge discovery for infrastructure planning, site assessments, disaster response routing, and proximity analysis. It could be stronger with an explicit 'use nbi.search for non-proximity queries' route, but the radius-based usage is unambiguous and the listed use cases give solid practical guidance.

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