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

Goes well beyond the annotations: it discloses idempotent semantics (existing account untouched), the side effect of creating an account at turbometrics.io, the conditional welcome email with a 60-minute password link, and the fact that no email is sent on the exists path. It even warns that the response does not mention the email, which is exactly the kind of behavioural detail annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false) cannot convey.

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 what the tool does and the created/exists branching, and every sentence carries behavioural information. It is somewhat long and repeats the email/created-exists point twice, plus an interjected provenance note, but there is little genuine padding.

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?

With no output schema, the description does the right thing by naming the created/exists response values and by pointing to the tools that surface scan results. It stops short of describing exact response fields or scan timing, but that information is available through the named sibling tools.

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?

Only one parameter and schema description coverage is 100%, so the schema already carries the domain semantics including the 'example.de' format hint. The description adds nothing about the domain argument beyond what the schema states, so the 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?

Specific verb + resource ('Aktiviert turbometrics ... für eine Domain') with the scope (per-domain, for turbopress customers) stated up front. It is clearly distinguishable from the sibling read tools get_performance_score/get_performance_findings and from start_performance_scan, which the description implies is made redundant by the automatic scans.

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?

Explains the two operating conditions (first activation creates the account, subsequent calls leave it unchanged) and routes the agent to the right follow-up tools (get_performance_score, get_performance_findings). It does not explicitly state when NOT to use it versus start_performance_scan, so there is a small gap.

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