take_snapshot

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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description reinforces it ('reads the page without changing it') and adds useful context the annotations don't carry: it returns the whole tree unfiltered, so large pages produce long output. No mention of any rate limits or truncation behavior beyond output length, which keeps it short of a 5.

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?

Front-loads what is returned before the routing advice and the output-size caveat. Dense but every clause earns its place — the sibling comparisons and the long-output warning both change agent behavior.

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?

For a one-parameter read tool with no output schema, the description supplies the return shape (indented text, role + name, nested by structure) and the output-size caveat, plus the decision boundary against two siblings. Nothing an agent needs to call it correctly is missing.

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 (sessionId) with 100% schema description coverage that already explains it comes from open_browser_session and errors if missing. The description adds no parameter-level detail, which is acceptable given the schema does the work; baseline 3 applies.

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?

States a specific verb and resource ('Return the accessibility tree of the session's active tab as indented text') and enumerates the content: roles, names, links, buttons, headings, form fields, labels, current values. This makes it immediately distinguishable from take_screenshot and evaluate.

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?

Explicitly routes between siblings: use this to find what's on the page and what to click or type into, 'far more cheaply than take_screenshot'; use take_screenshot when visual layout matters; use evaluate for data not shown as text. Both the when and the when-not are named with concrete alternatives.

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