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

Annotations declare a non-readOnly, openWorld, non-idempotent mutation, and the description adds real behavioral detail beyond them: it previews by default and only commits when confirm is true, and it discloses side effects (creates a stream, links to the client, emits a measurement ID). It omits any idempotency/duplicate-creation warning, which matters given idempotentHint=false.

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?

Three sentences, front-loaded with the action and follow-up context, with no filler. The long parenthetical about the G- measurement ID and the run-on follow-on list make it slightly dense but each clause carries information.

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 a 7-parameter mutation with no output schema, the description covers purpose, sequencing, preview behavior, and the key returned value (measurement ID). It lacks auth/permission requirements and error/retry behavior, but is otherwise sufficient to invoke correctly.

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 71% and the description compensates for the key uncovered parameter by explaining confirm ("Previews unless confirm is true") and clarifying that client drives linking. It also names the follow-up parameter binding (ga4_id = measurement_id). Currency, one of the uncovered params, is not explained.

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 ("Create a GA4 property") and enriches it with scope: it creates the web data stream, yields the G- measurement ID, and links the property to a named client. This clearly differentiates it from siblings like ga4_create_key_event and ga4_link_google_ads, which appear later in the workflow.

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 strong usage context ("Day-one set-up for a new client") and an explicit follow-on chain (ga4_create_key_event, wp_install_tracking, ga4_link_google_ads). It does not state when NOT to use it (e.g., if a property already exists), so it stops short of full when/when-not coverage.

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