Da Distinct Values

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description adds that it returns verifiable structured results and that write/path restrictions depend on service capabilities, which is mild extra context but vague. It does not contradict the annotations.

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?

The description is two short sentences and front-loads the purpose. There is minor redundancy in '唯一值da distinct values' and the second sentence about write/path restrictions is largely irrelevant for a read-only tool, but it is not bloated.

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?

Although an output schema exists and annotations cover safety, the definition is incomplete for a five-parameter read tool with 0% schema description coverage. It omits parameter semantics, usage context, and limits, leaving an agent without enough information to call it correctly without inspecting the schema.

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 0% and the description mentions none of the five parameters (dataset_path, field_name, max_values, where_clause, max_rows_scanned). The description fails to compensate for the absent schema documentation, leaving parameter meanings entirely unexplained.

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?

The description states a specific verb and resource: 'read unique values' (读取唯一值). This distinguishes the tool from siblings like da_query_rows or da_table_sample. However, it does not explicitly differentiate from other value-listing siblings such as list_domains or list_subtypes, so it stops short of a 5.

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?

No guidance is given about when to use this tool versus alternatives such as da_query_rows or list_fields. The clause about write and path restrictions being subject to service capabilities is not usage guidance for a read-only operation. No prerequisites or exclusions are stated.

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