list_tabs

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

The description explicitly discloses side effects ('none (read-only registry snapshot)') and describes the fallback behavior when no tabs are registered, including the note in the response. With no annotations provided, this fully carries the behavioral transparency burden and exceeds it by explaining return structure and special cases.

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 description is structured with distinct sections (purpose, side effects, returns, fallback, usage, alternative) and front-loads the core purpose. It is slightly verbose but every sentence adds unique, relevant information, so no waste.

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 simple read-only tool with one optional parameter and no output schema, the description covers return format (active_tab_id, tabs array, note), side effects, fallback behavior, usage guidance, and alternatives. 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?

The single parameter (instance_id) is already fully described in the schema (100% coverage), and the description adds no additional semantics beyond the schema's mention of omitting it for the default instance. It does tie the parameter to discovering Tab IDs, but that's purpose rather than parameter meaning, so a baseline 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?

The description states a specific verb ('Lists'), resource ('all tabs'), and scope ('in the specified Chrome instance'), and explicitly distinguishes itself by noting it returns Tab IDs for use with other tools, making it unambiguous against siblings like list_instances and open_tab.

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 clearly states when to use the tool ('to discover Tab IDs before passing tab_id to other tools') and provides an explicit alternative ('list_instances' for enumerating instances), enabling proper routing without inference.

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