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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds the non-mutating data source (dumpsys gfxinfo), but discloses no operational caveats such as whether the app must be running or that gfxinfo stats are cumulative since last reset.

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?

A single front-loaded sentence with zero filler; the parenthetical metric list earns its place by telling the agent exactly what comes back. No redundant restatement of the title or schema.

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 usefully enumerates the returned metrics (jank %, percentiles, missed vsyncs). Combined with fully documented params and safety annotations, this is nearly complete, though it omits prerequisites for obtaining meaningful stats.

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%, with both 'pkg' and 'serial' documented (including an example and a reference to device_list). The description adds no further parameter meaning, which is the correct baseline 3 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?

The description states a specific resource and scope (FPS/jank stats for a package) and even names the underlying mechanism (dumpsys gfxinfo), so an agent can tell what it returns. It does not explicitly differentiate from potential siblings like android_performance_snapshot, so it falls short of a 5.

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?

Usage is implied by the metric provided (fetch FPS/jank for a package), but there is no explicit when-to-use, when-not-to-use, or named alternative such as android_performance_snapshot. This is the minimum-viable level of guidance.

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