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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so safety is covered. The description adds real behavioral value beyond them: the size and source of the corpus (all 8,764 CDFI Fund rows), the returned listed/not-listed status plus provenance fields, and the hard 2010 vintage constraint.

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?

Front-loads the yes/no question, then supports it with corpus/return details, the vintage constraint, and a scope disclaimer. Every sentence earns its place and nothing is padded, though the paragraph is fairly dense for a single-lookup tool.

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?

With no output schema, the description carries the burden of describing returns, and it does list them (status, geography, tract type, ACS source, official notices, provenance). Combined with the vintage constraint and scope disclaimer, it is largely complete for calling the tool correctly, missing only an explicit sibling-routing rule.

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%, so the GEOID format, the fixed-2010 vintage, and the markdown/json enum are all already documented in the schema. The description's 'never submit a 2020 tract identifier' warning restates the schema's own note, so it adds emphasis but little new semantics — baseline 3 applies.

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?

Uses a specific verb+resource ('exact lookup' of a Qualified Opportunity Zone designation) and frames it as a yes/no question about one GEOID, which cleanly separates it from search/compare/summarize siblings by implication. It stops short of naming an alternative sibling explicitly, so the differentiation is inferable rather than stated.

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 opening question establishes the exact use case, and the closing sentence draws scope exclusions ('not parcel confirmation or tax/legal advice'), effectively steering away from parcel_* siblings. It does not, however, name a sibling with its own selection condition (e.g., when to use search_designations instead).

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