Update Contact

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

With no annotations (no readOnlyHint or destructiveHint), the description carries the full burden of behavioral disclosure. It only states 'Update fields' but does not explain whether this performs a full replacement or partial update, what happens if the contact_id is invalid, or any other side effects. This is insufficient for safe agent use.

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, concise sentence that gets straight to the point. There is no wasted text. However, it could benefit from slightly more detail without becoming verbose.

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 that this is an update operation with multiple optional fields and an output schema (not shown), the description lacks critical context such as whether missing fields are preserved or cleared, and what the return value contains. The agent cannot infer proper usage from this minimal description alone.

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 0%, and the description does not mention any parameter. The input schema includes 6 parameters with anyOf null, but the agent receives no guidance on which fields can be updated or that they are optional. The description fails to add meaning beyond the raw schema.

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 uses a specific verb ('Update') and a clear resource ('an existing contact'), making the tool's purpose unambiguous. It effectively distinguishes this tool from siblings like contacts_create, contacts_delete, and contacts_get.

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?

No guidance is provided on when to use this tool versus alternatives (e.g., contacts_create for new contacts). The phrase 'on an existing contact' weakly implies a precondition, but no explicit when-to-use or when-not-to-use information is given.

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