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

Annotations declare readOnlyHint=false, destructiveHint=false and idempotentHint=false, so the safety profile is already carried structurally. The mention of confirm and idempotency validation restates schema behavior rather than adding context; there is no disclosure of whether the fields object merges with or replaces existing customer data, which is the key unknown for a partial-update tool.

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 compact sentences with the resource and scope front-loaded and no filler. It is efficient, though it spends its second sentence repeating schema-level facts instead of resolving real ambiguities.

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 6-parameter mutation with a nested fields object and no output schema, the annotations plus full schema coverage carry most of the load. Still missing is update semantics (merge vs overwrite of unspecified fields) and what the response returns, so it is adequate but not complete.

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 both required and optional parameters (including the nested fields object) are already documented in the schema. The description adds no syntax, format, or merge/replace semantics beyond what the schema states, so the baseline 3 applies.

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 ('Update an existing customer') and situates it in the CRM, which distinguishes it from create_customer and get_customer_details in the sibling list. It stops short of naming the record-lookup or scope rules that would make it 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?

The description never says when to reach for update_customer instead of create_customer or get_customer_details, nor what prerequisites exist before calling it. The only usage hint, 'confirm... dry-run', is already written into the schema, not the description.

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