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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the write-safety profile is covered. The description adds the deduping behavior, but it never says what happens on a dedupe hit (error, merge, skip) or what confirm=false actually returns, and "supports idempotency validation" sits in tension with idempotentHint=false without explaining that the key is what makes retries safe.

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?

Two short sentences with no filler, and the core action is front-loaded ahead of the capability note. Nothing can be trimmed without losing information.

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 9-parameter mutation tool with no output schema, the description covers the action and two key behaviors but omits the dedupe outcome, error conditions, and required auth context. Annotations carry the safety profile, so this is adequate but leaves real gaps an agent would hit at call time.

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%, so all nine parameters are already documented, including the deduping notes on email/phone and the dry-run semantics of confirm. The description only restates those same two concepts and adds no format, default, or constraint detail beyond the schema; 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 ("Add a new customer to the CRM") and adds a distinguishing qualifier ("with deduping"). It separates the tool from read-oriented siblings like get_customer_details, though it never names a sibling explicitly, so it falls short of 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?

"Supports confirm and idempotency validation" implies a preview-then-commit workflow, which is useful implied usage. However, there is no explicit when-to-use/when-not guidance and no routing to alternatives such as get_customer_details for checking existing customers before creating one.

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