update_contact

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

The description discloses a concrete behavioral consequence: setting status to 'unsubscribed' immediately excludes the contact from every future campaign. This goes beyond the annotations, which already indicate idempotent and non-destructive, by explaining a customer-facing side effect.

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 sentences with a front-loaded main action and a key consequence. No redundant filler or repetition of schema details, every clause serves a purpose.

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?

The tool has 9 parameters and no output schema. The description does not state what the tool returns (e.g., updated contact object vs. success indicator) or how partial updates are handled. While the schema covers parameter details, the missing return semantics leave a gap for the agent to know what to expect.

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 100%, so baseline is 3. The description adds meaning by clarifying that 'email' is the identifier and by giving the status parameter real-world consequences for 'unsubscribed'. This adds value over the schema's basic field descriptions.

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 action: 'Update an existing contact by email address' with a specific verb and resource. It also highlights a key sub-feature (changing subscription status). It distinguishes from sibling tools like create_contact or import_contacts by emphasizing 'existing'.

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 phrase 'existing contact' implies it is used for updating rather than creating, but the description does not explicitly state when to use this tool instead of alternatives. It offers no exclusions or cross-references to sibling tools like create_contact or import_contacts.

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