Update Contact

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

With no annotations provided, the description carries the burden of behavioral disclosure. It states 'Update' which implies mutation, and explicitly mentions the SUBREG_READONLY=false requirement, which is a useful behavioral constraint. However, it does not disclose side effects, error behavior, or return values, leaving notable gaps for a mutation tool.

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 two sentences: the first clearly states the action, the second provides a prerequisite and a reference. There is no fluff, redundancy, or extraneous details. The structure is front-loaded with the core purpose and uses the second sentence for additional context.

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 no output schema, no annotations, and a nested 'params' object with loose additionalProperties, the description is incomplete for a mutation tool. It provides a prerequisite and a manual link, but does not describe return values, error conditions, or the exact fields expected in params. The external link helps but the in-description coverage is insufficient for an agent to fully understand the tool's behavior without extra lookup.

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?

The input schema has 0% description coverage and provides only 'params' as an object with additionalProperties true. The description compensates by referencing the 'Subreg Update_Contact schema' and linking to the manual, which gives a canonical definition of the params structure. This adds meaning beyond the empty schema, but it does not inline the actual parameter details, so the agent still needs external lookup.

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 begins with 'Update an existing contact object,' which clearly states the action (update) and the resource (contact object). It also explicitly says 'existing,' distinguishing it from create_contact and other sibling tools. This is a specific verb+resource combination that leaves no ambiguity about the tool's function.

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 description implies when to use the tool (when updating an existing contact) and provides a clear precondition: 'Requires SUBREG_READONLY=false.' It does not explicitly mention alternatives such as create_contact for new contacts, but the word 'existing' offers contextual guidance. This is clear context without explicit exclusions.

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