observe

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

No annotations are provided, so the description carries the full load, and it does disclose non-obvious traits: the call is a read (non-mutating), it returns diff-style output relative to the previous call (making it stateful/history-dependent), and it surfaces only *new* console errors. That statefulness is real behavioral context an agent cannot infer from the schema. It stops short of 5 because payload size, cost, and whether the diff baseline resets are unstated.

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 sentence with the core action front-loaded and every clause contributing distinct return-content information. The parenthetical of implementation identifiers is slightly heavier than an agent strictly needs but still earns its place by grounding what 'state' means.

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 and no annotations, the description is the only source of return-value information, and it enumerates the payload contents well enough to set expectations. The remaining gap is that it doesn't say how the 'since the last observe' baseline is established or reset, which matters for a diff-returning 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?

Only one parameter and schema coverage is 100%, so the schema already explains `game`, including the 'main' default and subagent scoping. The description adds nothing about the parameter, so the baseline of 3 is appropriate.

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?

Specific verb ('Reads') plus a precisely scoped resource ('the open page's state') and an enumeration of what comes back: state JSON, three.js object names, renderer counts, new console errors, and deltas. An agent can tell this is a state-inspection tool. It never names or contrasts against siblings like `look`, `eval`, or `perf`, which likely overlap on page inspection, so it stops 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 only implied: 'what changed since the last observe' hints at a poll/verify loop after making changes, but there is no explicit when-to-use, when-not-to-use, or 'use X instead of this' routing. With `look`, `eval`, and `perf` as siblings, an agent must guess which observation tool to pick.

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