browser.list_tabs

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds the behavioral traits 'currently open' (indicating a snapshot) and 'for one session' (scoping the operation), which go slightly beyond annotations but do not disclose details such as return format, pagination, or how tabs are represented. Given the annotations, this is adequate but not rich.

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 nine-word sentence that is front-loaded with the action and resource, contains zero filler, and communicates the core scoping constraint. There is nothing extraneous; it is as concise as a description for this simple tool can be.

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 low-complexity, read-only tool with one well-documented optional parameter, the description plus annotations and schema provide everything an agent needs to invoke it correctly. The absence of an output schema is acceptable because the tool's purpose strongly implies a list result, and the schema explains how to get a session_id. No critical gaps remain.

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 session_id parameter is described in detail (source, optionality, fallback to observe/act tools). The tool description itself does not add parameter semantics beyond the phrase 'for one session', which merely restates the parameter's role. Since the schema carries the weight, the baseline of 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?

The description uses a specific verb ('List'), a clear resource ('currently open tabs/pages'), and a scoping constraint ('for one session'). This distinguishes it from siblings like list_sessions (which lists sessions, not tabs) and activate_tab/close_tab (which mutate tabs rather than list them). An agent can tell exactly what this tool does without opening the schema.

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?

The description does not explicitly state when to use this tool versus alternatives, nor does it name a sibling like list_sessions as a prerequisite. The parameter description hints that session ids come from browser.create_session or browser.list_sessions and that observe/act tools create one when none exists, which implies the session-management workflow, but this is not framed as a when-to-use rule for list_tabs itself. The usage context is implied rather than explicit.

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