Mariana Google MCP

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

With no annotations provided, the description carries full responsibility for behavioral disclosure, yet it omits critical details: it does not describe what contact fields are returned, whether pagination tokens are used beyond the max_results limit, or the authentication scope required. The phrase 'optionally filtered' implies group omission returns all contacts, but this is inferred rather than explicit.

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 9-word sentence that front-loads the core action ('List Google Contacts') and efficiently qualifies it with the optional filter clause. There is no redundant or wasted text, though extreme brevity comes at the cost of the completeness expected for a tool lacking an output schema.

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 absence of an output schema and annotations, the description inadequately prepares an agent for invocation. It fails to describe the return structure (e.g., whether it returns full contact objects or summaries), error conditions (invalid group names), or the default behavior when all optional parameters are omitted.

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 description mentions 'optionally filtered by contact group,' which aligns with the 'group' parameter in the schema. However, with schema description coverage at 100%, the schema already documents all three parameters (group, account, max_results). The description adds no semantic depth regarding the 'account' parameter (primary vs. secondary accounts) or the pagination behavior implied by 'max_results.'

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 states 'List Google Contacts, optionally filtered by contact group,' providing a clear verb (List) and resource (Google Contacts). However, it fails to distinguish from the sibling tool 'contacts_search,' leaving ambiguity about whether this tool performs text-based searching or only group-based enumeration.

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 provides no guidance on when to use this tool versus alternatives like 'contacts_search.' It does not specify prerequisites (such as authentication state) or exclusion criteria (e.g., when filtering by group is insufficient and search is required).

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