Check DataLayer

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

Annotations already supply readOnlyHint=true, and the description adds meaningful context: it loads the page in a headless browser, waits for runtime state, and looks for a specific anomaly (dataLayer redefinition after GTM init). No contradiction with the read-only annotation; the description supplements it.

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?

Two sentences, no filler. The core function is front-loaded and the enumerated checks are packed into the second sentence without redundancy.

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?

The description tells the agent what it checks and how (headless browser, runtime), which is sufficient to invoke it correctly. The absence of an output schema is partly mitigated by the explicit list of checks, though the exact result shape is left unspecified.

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 100%, so both url and wait_ms are already documented. The description does not add parameter-level detail, which is acceptable given the schema handles it; 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?

Description opens with a specific verb-resource pair: 'Inspect window.dataLayer at runtime using a headless browser,' which clearly distinguishes it from static HTML checks like check_gtm_snippet or network-based tracking checks. It then enumerates the exact checks performed (existence, contents, GTM/gtag load state, suspicious redefinition patterns), so an agent can tell what this tool is for.

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 phrase 'at runtime using a headless browser' implies the tool is for observing the live dataLayer state, rather than static source inspection. However, it does not explicitly say when to prefer this over siblings such as check_gtm_snippet, intercept_tracking_requests, or audit_tracking, nor does it state any exclusions.

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