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

Annotations already declare readOnlyHint=true, and the description's 'Read-only' merely repeats that (no credit). However it adds genuine behavioral context: the meaning of 'merged or not' on linked pairs and the required preview-then-confirm merge workflow. It stops short of describing the pair shape or ordering.

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?

Front-loaded with the resource definition, then the status semantics, then the merge hand-off. Every sentence carries information, though the final merge-workflow sentence is slightly tangential to a list operation.

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?

With only one optional enum parameter, no output schema, and annotations covering the safety profile, the description supplies everything needed: what is listed, what each filter returns, and the next step for acting on results. Nothing an agent needs to invoke it correctly is missing.

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%, so the enum is already documented, but the description adds real meaning beyond it: 'to_review' = pairs nobody has answered yet, 'linked' = pairs the user confirmed as the same person, each flagged merged/unmerged. That exceeds the baseline 3 when the schema does the heavy lifting.

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?

States a specific verb (List) and resource (pairs of contacts that look like the same person), with the source of the data (the duplicate scan) named. An agent can distinguish this from siblings like merge_graph_objects or similar_objects without opening any schema.

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?

Explains what each status value selects and explicitly routes the agent to the alternative action (call merge_graph_objects with preview=true, then let the user confirm) for the merge case. The when-to-use and the follow-up path are both stated, not inferred.

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