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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false). The description adds genuinely useful behavior beyond that: it returns each value with its row count and orders results most-common-first, so the agent knows the return shape and ordering.

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?

Two sentences, zero padding, and the ordering/return behavior is front-loaded alongside the purpose. Every clause 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 simple 3-parameter read tool with no output schema, the description supplies purpose, use case, and return format, leaving little ambiguity. Only minor gaps like large-table cost or limit semantics remain, and the schema covers the limit default.

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 table, column, and the limit default of 50 are all documented in the schema itself. The description implies column/table are required by restating 'in a column' but adds no format or syntax detail, so 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?

States a specific verb+resource ('List the distinct values in a column') and clarifies the intent with a concrete use case (enum/value discovery for statuses or service types). It does not name a sibling such as describe_schema, but the operation itself is unmistakable.

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 clear context for when to reach for this tool ('for enum/value discovery — e.g. what statuses or service types exist'), which is exactly the decision point an agent faces. No explicit when-not guidance or named alternative is provided, so it stops short of a 5.

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