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Isopleth

by dev.isopleth
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Search the field catalog

search_fields
Read-onlyIdempotent

Search the field catalog by keywords such as 'flood zone', 'substation', 'wildfire' or 'broadband' to find field names for fetch_location, fetch_batch or parcel_enrich. With an empty query it lists the catalog itself, up to 200 fields per call, narrowed by preset or source to reach the rest. Division of the catalog tools: search_fields discovers names (with type, unit, source and description); describe_fields only looks up exact names already known and adds source URL, license, attribution and refresh interval; list_presets lists bundles. Matching: case-insensitive; every word must appear somewhere in the field name (underscores read as spaces), description or source id; optionally narrowed to one preset or source. Output: total matches, returned count and fields [{name, type, unit, source, description}]; no match gives total 0 and an empty list. Cost: Free. Behavior: read-only (no side effects); needs an API key or OAuth; each call counts toward the per-minute request limit (Free 10, Starter 60, Pro 300). Reads the gateway's field catalog, cached for up to 1 hour, so no live data source is called and results return quickly. Errors: preset_unknown (lists known presets).

Input Schema

NameRequiredDescriptionDefault
limitNoMaximum fields to return, 1 to 200 (default 40). total still counts every match.
queryNoSpace-separated keywords, all of which must match (substring, case-insensitive). Empty or omitted matches every field.
presetNoOptional exact preset name; only that preset's fields are searched.
sourceNoOptional source id prefix, case-insensitive (e.g. 'FEMA', 'USGS'); only fields from matching sources are searched.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

A4.8/5.0
Behavior5/5

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

Goes well beyond the readOnlyHint/idempotentHint annotations: discloses auth requirements (API key or OAuth), per-minute rate limits by tier, that results come from a catalog cached up to 1 hour with no live source call, the exact error code (preset_unknown), and the return shape with the no-match case. This is unusually rich behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose and sibling routing, then matching, output, cost, and errors; nearly every sentence carries information. It is dense and long, but the density is justified rather than padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, yet the description specifies the return fields, total vs returned count, and the empty-result case, plus errors and authentication. Nothing an agent needs to invoke this correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3; the description still adds matching semantics not in the schema, notably that underscores in field names are read as spaces and that matching spans name, description, or source id. It stops short of adding format detail for preset/source beyond what the schema already states.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Search the field catalog by keywords') and gives concrete example queries. It also explicitly delineates the division of labor against siblings describe_fields and list_presets, so an agent can route correctly without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly says when to use this tool ('discovers names') versus describe_fields ('only looks up exact names already known') and list_presets. It also documents the empty-query behavior and the preset/source narrowing path to reach results beyond the 200 cap.

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

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