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

Goes well beyond the readOnly/idempotent annotations by disclosing the billing model: 1 credit per building not opened in the last year, charged all-or-nothing, with already-opened buildings free. That cost/effect disclosure is exactly the kind of context annotations cannot carry. It omits response-format and partial-failure behavior, but the cost rule is the material risk here.

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 action and source of ids, then the return contents, then cost - a sensible order with no filler sentences. The mid-sentence enumeration of every returned field is long and dense, but with no output schema present it largely 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?

With no output schema, the description correctly compensates by listing the returned fields and `basis` values, and it discloses the credit cost, idempotency behavior, and an explicit scope exclusion. It is nearly complete; only the relationship to the get_building sibling for full single-building records is left implicit.

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% and the single `buildingIds` parameter is already self-documented with its 1-25 range. The description adds provenance (ids come from locked search rows or nearby address-lookup rows) but no syntax, deduplication, or ordering semantics, so the added value over the schema is modest. Baseline 3 is appropriate.

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?

Starts with a specific verb+resource ('Opens buildings') and pins down the exact input provenance (search rows with `locked` true, or `nearby` rows of an address lookup) and the full return payload. It also carves out an explicit boundary ('One building's whole record ... is not part of this result'), which lets an agent separate it from the bulk search and single-record siblings.

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?

Gives a clear usage trigger with quoted user phrasing ('open the top five', 'these three') and names where the ids must come from, which is real routing guidance. It stops short of naming an alternative tool (e.g. get_building) or stating when not to use this one, so it is clear context without explicit exclusions.

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