Update contact

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

No annotations are supplied, so the description carries the full behavioral burden. It usefully discloses partial-update semantics (only supplied fields change), which is real behavioral value, but says nothing about auth requirements, error behavior on a bad resourceName, or whether photoBytes replaces an existing photo.

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?

One compact sentence with the verb, resource, field list, and update semantics all front-loaded; no filler and nothing redundant.

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 an 8-parameter mutation tool with no annotations and no output schema, the description covers what can be changed and that updates are partial, but omits confirmation/return behavior and failure modes. Adequate but with clear 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 description coverage is 88%, so the schema already documents nearly every parameter; the baseline of 3 applies. The description enumerates most fields but omits 'account' and adds only the partial-update qualifier, so it does not meaningfully exceed the 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?

States a specific verb (Update) and resource (existing contact) plus the exact mutable fields, and the phrase 'existing contact' implicitly separates it from google_contacts_create. It does not name the sibling explicitly, so it stops short of a 5.

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?

Usage is only implied: 'update an existing contact' tells the agent the resource must already exist, and '(partial update by resourceName)' hints that resourceName comes from a prior lookup. There is no explicit when-to-use-vs-create guidance and no prerequisites or exclusions stated.

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