perf_timechart

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

With no annotations available, the description carries the full burden. It discloses the output ('returns the SVG file path and size') and the prerequisite ('Requires: perf timechart record'), but it does not mention limitations, error handling, or side effects beyond creating an SVG file. This partial transparency leaves gaps.

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?

The description is well-structured with a clear opening purpose, a 'Key parameters' summary, and separate lines for 'Output' and 'Requires.' It avoids unnecessary detail and stays within a compact size, though the parameter list is somewhat redundant with the 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?

Given the tool's complexity (17 parameters) and the existence of an output schema, the description provides adequate context about the tool's purpose and key options. However, it lacks guidance on when to use specific filters, how they interact, or typical workflows, leaving some gaps for a heavy parameterized tool.

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%, and the description only highlights a subset of parameters in a 'Key parameters' list without adding new semantic meaning. The baseline of 3 applies because the schema already documents parameters well; the description adds marginal value by emphasizing common filters.

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 clearly states the tool's primary function: 'Generate a timechart SVG showing CPU activity and task scheduling over time as a visual timeline.' This specific verb-resource pairing distinguishes it from sibling tools like perf_sched_map or perf_report, which focus on other forms of analysis or output.

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 provides clear context on when to use the tool by explaining 'Requires: perf timechart record' and listing key filters such as process, power_only, and tasks_only. However, it does not explicitly exclude alternatives or describe trade-offs compared to other perf visualization tools.

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