gmail_list_labels

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

Annotations already declare readOnlyHint/idempotentHint, so the 'Read-only' sentence is redundant, but the description adds real cost information: include_counts triggers extra API calls. That is a behavioral trait not present in annotations.

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?

Four short clauses, each front-loaded with the essential fact: purpose, optional enrichment with cost, safety, and sequencing. Zero filler.

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?

A single optional boolean plus rich annotations and no output schema means little else is needed. Only the shape of returned label metadata is left implicit, which is a minor gap.

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% and the schema's own description of include_counts ('Estimate total/unread per label via filtered searches (extra API calls)') already covers both the meaning and the cost. The description largely restates it, so baseline 3 applies.

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 and resource ('Lists Gmail label metadata'), clearly distinct from the many message/thread/draft siblings and from gmail_apply_labels. It stops short of describing output shape, but the operation is unambiguous.

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?

Gives an explicit sequencing rule ('Use before gmail_apply_labels') and a conditional enrichment path via include_counts. No when-not guidance is given, but the primary use context is clear.

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