Retrieve a rule by ID to apply its constraints and examples during implementation, ensuring no required restrictions are skipped.
WHEN: implementing something covered by a named rule (constraints, networking, etc.). HOW: apply purpose/constraints/examples from the rule; do not skip constraints.
| Name | Required | Description | Default |
|---|---|---|---|
| ruleId | Yes | Rule identifier or filename |
Changes observed during successful MCP inspections.
v2.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description must disclose behavior, but it only offers usage guidance. It does not state that the tool is read-only, what it returns, or any error handling. The instruction 'do not skip constraints' is ambiguous about tool behavior versus agent behavior.
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 extremely concise, using a WHEN/HOW structure that front-loads the key context. Every word earns its place, though it could be slightly expanded for clarity.
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 read tool with one parameter, the description covers when and how to use it, but does not explicitly state what is returned (e.g., the rule content) or behavior on missing rules. Since there is no output schema, this is a gap.
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?
The schema covers the single parameter ruleId with a description. The tool description adds no additional meaning about the parameter, so it sits at the baseline 3 for 100% schema coverage.
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 does not explicitly state 'reads a rule' but implies it via 'WHEN: implementing something covered by a named rule.' It does not directly name the action or resource, and the sibling tools like read_skill and list_rules are not differentiated. The purpose is inferred rather than stated.
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 gives a clear condition for use ('implementing something covered by a named rule') and instructions on how to apply the rule ('apply purpose/constraints/examples; do not skip constraints'). It does not mention alternatives, but the WHEN clause effectively guides selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.