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

Annotations already declare read-only, idempotent, open-world behavior, so the safety profile is covered. The description adds real context beyond that: the size of the corpus (8,764 CDFI Fund rows), the enumerated return contents (listed/not-listed status, geography, tract type, ACS source, notices, provenance), and the fixed-vintage rule. It stops short of auth or rate-limit details, but adds substantive value.

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, front-loaded with the core question, then the mechanics, then the vintage warning and scope caveat. The enumerated return list is somewhat long, but each sentence carries distinct information and nothing is wasted.

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 compensates by enumerating what is returned, and it covers the critical vintage constraint and a scope disclaimer. For a single-identifier lookup tool, an agent has everything needed to call it correctly and interpret the result.

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 baseline is 3, but the description adds a genuine usage warning: tract_vintage is fixed to 2010 and a 2020 identifier must not be substituted. That reinforces and operationalizes the schema's 'Must be 2010' note rather than merely restating it.

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 precise verb (exact lookup) and resource (2010 census tract GEOID against the final 2018-cycle Qualified Opportunity Zone corpus), framed as a direct yes/no question. It is clearly distinguishable from the search/compare/summarize siblings because 'exact lookup' implies a known identifier rather than a query.

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 phrase 'exact lookup' plus the constraint 'never submit a 2020 tract identifier as if it were equivalent' gives clear conditions for correct use, and 'not parcel confirmation or tax/legal advice' sets scope boundaries. However, it never explicitly names the alternative (e.g., opportunity_zones_search_designations) for when the agent lacks an exact GEOID, so routing is left to inference.

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