Modify an existing ServiceNow ACL rule using its sys_id and field updates for active status, script, roles, or conditions. Adjust access control settings without recreating the rule.
Update an existing ACL rule (requires SCRIPTING_ENABLED=true)
| Name | Required | Description | Default |
|---|---|---|---|
| fields | Yes | Fields to update (active, script, roles, condition, etc.) | |
| sys_id | Yes | ACL sys_id |
Changes observed during successful MCP inspections.
v1.0.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide safety hints (readOnlyHint=false, destructiveHint=false, idempotentHint=true). The description adds the requirement that SCRIPTING_ENABLED=true must be set, which is useful beyond annotations. However, it does not disclose whether the update merges or replaces fields, nor does it mention potential side effects or permission requirements beyond the scripting flag.
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 a single sentence that immediately states the action and the requirement. It contains no filler or redundant wording, making it highly concise and front-loaded.
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 update tool, the description covers the core purpose and a critical prerequisite. The schema explains the parameters, and annotations cover safety. It does not describe the return value, but no output schema exists and update tools often return minimal data. The main missing piece is explicit confirmation that only provided fields are updated, but overall it is sufficiently complete.
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%: both `sys_id` and `fields` have descriptions, with `fields` listing examples (active, script, roles, condition). The tool description itself adds no parameter-specific information beyond what the schema already provides, so it stays at the baseline of 3.
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 clearly states the action ('Update') and the resource ('an existing ACL rule'), and the word 'existing' differentiates it from creation tools like create_acl. It also adds a key prerequisite (SCRIPTING_ENABLED=true), making the tool's purpose unambiguous.
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 implies usage for updating already-existing ACL rules, which distinguishes it from create_acl. It also states a specific prerequisite (SCRIPTING_ENABLED=true). However, it does not explicitly name alternatives or state when not to use this tool, so it lacks full exclusionary guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.