Update contact

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

There are no annotations provided, so the description carries the full burden. It discloses partial update behavior ('only the provided fields are changed') which is good, but it doesn't state whether the update is idempotent, what happens with invalid or missing fields, whether it requires authentication, or what the response looks like. It adds some value beyond the schema.

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 a single sentence that is direct and front-loads the key behavior. No fluff, every word earns its place.

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?

Given the tool has 5 parameters and no output schema, the description is sparse. It tells the agent the core behavior but lacks guidance on how to identify the contact (e.g., use 'keys'), what 'customFields' expects, or any restrictions. It's adequate but leaves notable gaps.

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 only 20%, and the description adds minimal parameter semantics beyond the schema. It only mentions custom fields explicitly; it doesn't elaborate on 'keys' or other parameters. However, the schema already has a detailed description for 'phone', but the others are bare. The description doesn't compensate for the low coverage.

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 clearly states the tool updates a contact and specifies that only provided fields are changed, distinguishing it from create_contact and get_contact. It mentions custom fields are handled under 'customFields'. This is clear but doesn't explicitly differentiate among the many update_* siblings.

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 implies that you use this tool to update an existing contact's fields, and that only provided fields are changed, which is useful guidance. However, it doesn't explicitly state when to use it over create_contact or get_contact, nor mention any prerequisites like needing an existing contact ID (though 'keys' parameter hints at that).

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