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

With no annotations provided, the description carries the full behavioral burden and does so well: it discloses that transactions and aliases move, that the target silently wins on defaultCategoryId conflict, that the source is deleted, and that finance:delete scope is required. This gives the agent a clear picture of the destructive and conflict-resolution behavior beyond the input schema.

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 compact and front-loaded: it states the operation first, then the key side effects, then the use case and permission requirement. Every sentence adds distinct, necessary information with no waste.

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 two-parameter merge tool with no annotations and no output schema, the description supplies the important behavioral, conflict-resolution, deletion, and permission context an agent needs to invoke it safely. Return values need not be explained because no output schema exists.

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 description coverage is 100%, and the schema already explains that sourceId is deleted and targetId is kept. The description reinforces the source/target relationship but does not add new syntax, constraints, or format details for either parameter, so the schema does the heavy lifting and a baseline 3 is appropriate.

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 names a specific verb and resource ('Merge a source Payee into a target Payee') and immediately distinguishes the operation from simple deletion or update by explaining that transactions and aliases move to the target while the source is deleted. An agent can identify this as a deduplication/merge operation without checking sibling tools.

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?

It gives a clear trigger ('Use to dedupe near-duplicates like "Amazon" and "AMZN MKT"') and states a required scope ('Requires finance:delete scope'), which helps the agent decide when this tool is appropriate. It does not explicitly name alternatives such as update_payee or delete_payee, so it falls short of the highest bar.

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