frames_list

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

No annotations are supplied, so the description carries the behavioral burden. It discloses the reachability limitation ('every iframe the extension can reach') and the shape of the result, and 'List' implies a read-only, side-effect-free operation. It does not state error behavior for unreachable frames or any permission constraints, so it falls short of fully covering a no-annotation tool.

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?

Two sentences, no filler: the first defines what is listed and returned, the second gives the trigger and the follow-up action. The most actionable content (when to reach for this tool) is placed second but still immediately readable.

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?

There is no output schema or annotations, so the description must explain returns and behavior; it does name the returned fields (id and URL) and the frame-reachability caveat. It leaves unanswered what happens when no frames are found or when an iframe is unreachable, which for a no-annotation tool is a modest but real gap.

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 coverage is 100% and the single tabId parameter is already documented with its default ('agent's tab'), so baseline is 3. The description mentions frameId/allFrames:true, but those belong to other tools rather than clarifying this tool's input; it adds no syntax or format detail about tabId itself.

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 ('List the tab's frames') and defines scope precisely: 'the top document plus every iframe the extension can reach'. It also names the return contents (frame id and URL), which lets an agent distinguish it from tabs_list without opening schemas.

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?

Gives an explicit trigger condition — 'Use it when a selector that should match does not' — and a concrete next step ('pass frameId (or allFrames:true) to act inside it'). This is a when-to-use rule tied to observable failure, which is exactly what an agent needs.

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