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

Annotations already cover readOnly/idempotent/non-destructive, but the description adds meaningful behavior: it operates per-page with no device-wide mutation and installs no certificate, and the native-code exclusion clarifies scope. The 'first match wins' ordering detail is useful context a caller would otherwise not know.

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-loads the core purpose, then qualifies scope. Slightly wordy with the emphatic 'and never will be by this tool' and the certificate sentence, but every element is relevant and no sentence is pure filler.

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 read-only list tool with no output schema, the description conveys what is listed and the ordering rule, which is most of what a caller needs. It stops short of describing the shape/fields of the returned route list, so it is not quite fully complete.

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?

Single parameter (udid) with 100% schema description coverage, so the schema already documents it fully and the description adds nothing about the parameter. Baseline 3 applies when the schema does the heavy lifting.

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 (browser mock/abort routes currently registered for this device), plus the ordering semantics 'in match order (first match wins)'. This lets an agent separate it from the mock_add/remove/clear/status siblings without opening a schema.

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?

Clear context for when this tool applies: browser/WebView pages only, and explicitly NOT native app code requests. This scoping steers the agent, though it never names an explicit alternative (e.g., traffic_mock_list for native) or states the reverse 'use this when' condition.

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