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

Annotations already carry the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower. The description adds genuine value beyond annotations by declaring the result content (GEOID, name, FIPS, areas, interior point), which is important given there is no output schema. No contradiction with annotations; 'AUTHORITATIVE' also conveys data-source trustworthiness.

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?

Three sentences with zero filler, front-loaded with the authoritative query capability first, followed by the preference rule with concrete examples, and ending with the required dependency on tigerweb_list_layers. The most critical routing information appears first and every sentence earns its place.

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 an 8-parameter tool with no output schema, the description adequately covers return contents and data authority while the schema covers parameter syntax. The main gap is the missing contrast with tigerweb_geography_at_point, which would complete the routing picture for point-based reverse lookups. This is a minor omission given the strong annotations and full schema coverage.

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%, and the schema already documents the ArcGIS WHERE clause syntax (FIPS as strings, AND/OR/LIKE, default '1=1') and that layer_id comes from tigerweb_list_layers. The description's example domains ('every census tract in Cook County') hint at WHERE-clause construction but add marginal value over the schema's own example. Baseline 3 is appropriate since the schema does the heavy lifting.

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 verb and resource: 'query any TIGERweb layer with an ArcGIS WHERE clause' returning 'GEOID, name, FIPS components, land/water area and interior point.' The 'AUTHORITATIVE' framing plus 'PREFER OVER WEB SEARCH' distinguishes it from the search siblings, and referencing tigerweb_list_layers for layer_id positions it against its companion 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?

Explicitly tells the agent when to use it: 'PREFER OVER WEB SEARCH' with concrete, discriminating example queries ('every census tract in Cook County', 'all ZCTAs in Rhode Island'). It also gives a cross-tool dependency (get layer_id from tigerweb_list_layers). However, it provides no when-not guidance and never contrasts with the natural sibling alternative tigerweb_geography_at_point for point-based lookups, so it stops short of a full exclusion set.

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