Merge End-Users

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

Discloses effects beyond annotations: writes are performed, FK rows are re-pointed, sources are tombstoned, and the operation is reversible for 30 days. Annotations are destHint=false, etc., but the description adds meaningful context without contradiction.

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?

Single paragraph front-loaded with the main action and result. Every sentence adds value: what the tool does, how IDs come from candidates, reversibility, and required params. No wasted words.

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?

Given no output schema, the description mentions return includes merge event id and references list_identity_merges for later recovery. Covers all key aspects: inputs, effects, reversibility, and prerequisites. Could specify return format more but sufficient for a write operation.

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 descriptions for all three parameters. The description reinforces that 'target_end_user_id' and 'source_end_user_ids' are required and links them to get_device_candidates. Adds minor value beyond schema by clarifying that source IDs are UUIDs from candidates.

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 ('Merge source end-users into a target'), specifies the resource ('end-users'), and mentions the outcome ('return the merge result, including the merge event id'). It distinguishes from sibling tools like 'unmerge_end_users' and 'get_device_candidates'.

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?

Provides explicit guidance: 'Get the candidate ids from get_device_candidates first — never guess which users to fold together.' Also notes the operation is reversible via 'unmerge_end_users' and that required parameters are both given. Lacks explicit when-not-to-use but context is clear.

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