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

Annotations already cover readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is handled. The description adds genuinely non-redundant behavior: matching is first-match-wins, the effect is scoped to the page, no certificate is installed, and nothing is changed device-wide. It stops short of describing the returned entry structure.

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 compact sentences, front-loaded with what is listed and in what order. The two follow-up sentences are scope/reassurance rather than filler, though the 'never will be by this tool' clause is slightly emphatic for the space it occupies.

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 single-parameter read-only list with full schema coverage and annotations, the description supplies the missing behavioral context (ordering, scope limits). Since there is no output schema, it would be marginally better if it hinted at the fields of a returned route, but nothing critical to invoking it correctly is absent.

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?

There is only one parameter (udid) and schema description coverage is 100%, so the schema already documents it fully. The description contributes no additional meaning about the udid argument, which is the baseline-3 case for a fully covered single parameter.

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 (List) and resource (Chrome/WebView mock/abort routes registered for this device), plus the ordering semantics (match order, first match wins). That is enough to distinguish it from mock_add/mock_remove/mock_clear, but it does not explicitly contrast itself with the close sibling mock_status, which is the one an agent could plausibly confuse it with.

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 description clarifies scope (web content only, native app requests not intercepted) which implicitly tells the agent when this tool is relevant, but it never names an alternative tool or states a when-to-use condition versus mock_status or the traffic-mock equivalents. Usage is inferable rather than stated.

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