Rules by purpose

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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is clear. Description adds behavioral detail that specific buckets exclude off-topic rules (R31/R32), providing extra context beyond 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?

Two sentences with no redundant words. The verb 'Filter' and resource are front-loaded, and every part adds value.

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 single-parameter read-only tool with full annotations, the description covers all necessary aspects: purpose, valid values, and special filtering behavior. No output schema is needed as return values are implied.

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% with an enum, but the description adds meaningful context: the table size (56 rules) and that certain buckets exclude specific rules. This enriches the parameter's semantics beyond the enum list.

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?

Description clearly states the tool filters a specific resource ('56-rule table') by purpose bucket, enumerating valid values and noting exclusion behavior. This is specific and distinguishes it from sibling tools like gkb_rule_detail or gkb_rules_index.

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?

Description explicitly tells when to use the tool (to filter by purpose bucket) and lists valid buckets. It does not mention when not to use it or alternative tools, but the context is clear given the distinct sibling tools.

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