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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true); the description goes beyond them by disclosing the returned G- measurement ID, the intended downstream use (GTM GA4 config tag), and the rejection behavior for foreign properties. It stops short of stating what happens if a stream for the same site_url already exists.

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?

Front-loaded with the action and the return value, then per-parameter notes in short labeled lines. No filler, though the per-parameter block could be extended to the two missing params at minimal cost.

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?

An output schema exists, so return-format detail is not required, and creation semantics are adequately framed. The incomplete parameter documentation (2 of 4 params, including a required one) leaves the definition short of what an agent needs to call it reliably.

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 0%, so the description carries the full burden, yet it only explains property_id and workspace. The required parameter site_url and the optional display_name are left completely undefined, which is a real risk for a required input.

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 ('Web-Datenstream für eine GA4 Property anlegen') plus the outcome (G- measurement ID). It is distinguishable from the sibling ga4_list_data_streams, though the description never names the sibling or the read counterpart explicitly.

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?

Provides useful preconditions rather than use-case routing: the property must belong to the workspace ('andere werden abgelehnt') and the workspace param is optional when only one exists. It never says when to choose this over alternative ways of setting up tracking (e.g. GTM, ga4_create_property).

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