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

Annotations already declare non-destructive but writing behavior; the description adds real value by scoping the mutation to this one open guest conversation's name only, and by treating reply_token as a secret that must not be shared. It does not cover failure modes (e.g., closed conversations, invalid/expired token) which would complete the behavioral picture.

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, front-loaded with the access keys and the primary timing cue, with no filler. The 'Return and use the stored customer.name' line earns its place because no output schema exists.

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 three-parameter write tool with no output schema, the description covers when to call it, the exact mutation scope, credential caution, and the return field to use. Missing only error/edge behavior for tokens or non-open conversations.

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?

With 0% schema description coverage, the description supplies the needed meaning: inquiry_id must already exist, reply_token is private and must never be shared, and customer_name must come from the customer rather than be invented. It adds no format/length guidance, but the schema caps handle that.

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 — saving the guest customer's name on an existing conversation via inquiry_id and reply_token — and immediately bounds it ('not email, phone or a signed-in identity'), which separates it from adjacent update_lead / save_inquiry_contact style operations.

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 concrete when-to-use condition ('especially before booking when a chat began as Website visitor') and several when-not rules ('never invent a name, create another conversation for a name change'). It stops short of naming a specific alternative tool for the excluded identity/email cases, so the agent must infer routing.

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