update_contact_custom_attributes

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

No annotations are provided, so the description carries the full behavioral burden. It states the mutation and one error case (500 on invalid JSON), but omits permissions, merge/replacement semantics, validation rules, reversibility, and success response behavior, which are important for an arbitrary custom-attribute update.

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?

The description is short and front-loaded, and it surfaces the useful invalid-JSON error behavior. There is minor redundancy from the repeated title, endpoint, and tags metadata, but no significant bloat.

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 mutation tool with a nested body object and no annotations or output schema, the description is incomplete. It does not clarify merge behavior, response shape, permissions, or the effect on unspecified custom attributes, leaving important invocation details unresolved.

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 the uuid path parameter and body object are already documented in the schema. The description only references the uuid path and does not add meaning about the body object, such as whether attributes are merged or replaced.

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 mutation ('Updates custom attributes') and scopes it to the contact on a conversation, distinguishing it from conversation-level attribute updates. It does not explicitly name or contrast with sibling tools such as update_conversation_custom_attributes.

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?

There is no when-to-use guidance, prerequisites, or comparison with alternatives like get_custom_attributes or update_conversation_custom_attributes. The endpoint and 'Tags: Contacts' imply API context but do not help an agent select the tool.

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