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list_stdlib_modules

List curated PerfettoSQL stdlib modules to discover available domains and views before writing SQL queries. Returns JSON with module, domain, views, description, and usage examples.

Instructions

List a curated set of PerfettoSQL stdlib modules. Returns a JSON array — each entry has module (the value for INCLUDE PERFETTO MODULE), domain (chrome / android / generic), views, description, and an illustrative usage query.

Use when: exploring what's available before writing SQL against an unfamiliar trace type, or discovering modules outside the dedicated chrome_* tools (memory, sched, wattson, v8, etc.). Call this before load_trace if you want to scope your analysis upfront — no trace needs to be loaded.

Don't use for: discovering all stdlib modules — this is a curated subset of the most useful ones. The exhaustive list lives at https://perfetto.dev/docs/analysis/stdlib-docs.

Parameters: none.

Then use execute_sql with INCLUDE PERFETTO MODULE <module>; SELECT ... (both can be in one call). If PERFETTO_TP_PATH points to a custom binary, some modules may not exist in that version — verify column names with list_table_structure if a query fails.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Behavior4/5

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

No annotations provided, so description carries full burden. It discloses that the list is curated and not exhaustive, and mentions behavior with custom binaries. Implies read-only operation though not explicitly stated. Good coverage of relevant behavioral traits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is well-structured with clear sections: purpose, usage guidelines, parameter statement, and follow-up instructions. It is front-loaded with key information. Slightly verbose but every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description fully explains the return format and fields. Covers edge cases (custom binary) and provides complete usage flow. For a tool with zero parameters, this is highly complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

No parameters exist, and schema coverage is 100%. The description states 'Parameters: none', which adds no additional meaning but is accurate. Baseline 3 per instructions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool lists a curated set of PerfettoSQL stdlib modules and returns a JSON array with specific fields. It distinguishes from sibling tools like execute_sql and list_tables, making its unique purpose obvious.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use (exploring available modules before writing SQL, discovering modules outside chrome_* tools) and when not to use (for exhaustive list, pointing to external URL). Provides guidance to call before load_trace and follow up with execute_sql.

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

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