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

Adds real behavior beyond the annotations: writes persist immediately and there is a hard cap of 50 per call, which is exactly the kind of limit annotations cannot express. It omits the approval_id human-approval flow, which matters for a non-idempotent mutation, so it is not fully transparent.

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?

Three short sentences, with the triggering condition front-loaded before the field rules and the size cap. The phrase 'ppl stores it immediately' is slightly ambiguous about what 'ppl' refers to, but nothing is padded.

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?

An output schema exists, so return values need no explanation, and the annotations cover the safety profile. What is missing is failure behavior: duplicate handling, partial success, and how the approval_id round-trip is supposed to work for a non-idempotent batch write.

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 both parameters are already documented, and the description largely restates them (first_name required, fact optional). It does add a usage heuristic for 'fact' — supply it when you know something — but says nothing about approval_id, so it stays at baseline.

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 and resource (batch import of contacts) and explicitly contrasts with the one-by-one path, so an agent can infer contacts.create is the alternative. It stops short of naming that sibling, which keeps it from a 5.

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?

Gives a concrete trigger: the account is empty and the user describes people conversationally ("my sister Maya, my coworker James"). It also tells the agent to prefer this over repeated single creates. It does not state what to do when the account already has contacts or when the batch exceeds 50.

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