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

With no annotations, the description carries the full load and does well: it discloses the return payload (matching zips, key investor metrics, a doorbase.app link each) and flags an important behavioral caveat that cap rates are a modeled band. It omits auth/rate-limit/pagination behavior (the limit cap of 25 is only in schema), keeping it from a 5.

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 tight sentences with the core question and return shape front-loaded; little waste. The question-style opener is slightly less direct than a declarative verb, but it 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 a 10-parameter, no-annotation, no-output-schema tool, the description covers purpose, return contents, and the key cap-rate caveat. It could say more about sorting/limit behavior, but nothing essential is missing for correct invocation.

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 80%, so the baseline is 3; the description adds real meaning by explaining that cap rates are a modeled band and min_cap_rate matches the band's high end, which the schema states mechanically but does not explain as modeled. It also enumerates the filter dimensions available.

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?

Opens with a specific framing ('Which US zip codes match these rental-market criteria?') and names the exact resource (30,000+ US zip codes) plus the filterable dimensions. This clearly sets it apart from siblings like get_zip_market (single zip), compare_zips, and top_markets.

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 implies a filter-based search but never states when to use this versus top_markets or compare_zips, nor any exclusions. The only usage hint ('Omit for nationwide') lives in the schema, not the description.

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