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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds substantive behavior by enumerating what hitch causes are surfaced, that memory growth is measured per level load, that the slowest recent hitches carry script attribution, and that multiplayer adds a `network` block. It does not discuss result size or ordering of the returned lists.

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 purpose is front-loaded in the first clause, but the body is a single sprawling comma-chained enumeration that is hard to scan. Most items are informative, yet the list is long enough that it should be broken up or trimmed of lower-value entries.

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 10 optional parameters, nested props object and no output schema, the description appropriately documents the returned structure in detail, which the structured fields cannot supply. Remaining gaps (volume of output, how per-level and per-zone sections are ordered) are minor for an analysis 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%, so the schema already documents all 10 parameters including hours, props, by_prop and session_type. The description reinforces by_prop's effect on output rather than adding new syntax or constraints, which is the expected baseline when the schema carries the parameter burden.

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?

Opens with a specific verb+resource ("Frame-time breakdown for a game") and then enumerates the concrete content: percentiles vs budget, per-level p50/p95/p99, hitch causes, memory growth, slowest hitches. It also differentiates itself from the sibling glitchless_network by naming it as the deeper network source.

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?

It explains the operational mode switch clearly: "With by_prop, frame time, hitches and crash-free sessions per value of a session property", and routes network-focused questions to glitchless_network. It does not state when to prefer glitchless_overview or glitchless_session instead, so the guidance is clear but not exhaustive.

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