account_list

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

Annotations already declare readOnlyHint=true, but the description adds meaningful behavior beyond that: metadata-only results, cookie values are credentials that never leave the server, and each account is a stable device with reused UA and fingerprint. These details help an agent understand data sensitivity and account identity semantics.

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 a compact, front-loaded paragraph that first states the action, then the returned metadata, then a security note, then usage. Every sentence contributes a distinct, useful piece of information without repetition.

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?

No output schema exists, but the description lists the returned fields explicitly: name, cookie domains, cookie count, updated_at, last account_verify verdict, and persona User-Agent. Combined with the readOnly annotation and zero-parameter schema, this gives the agent enough context to invoke the tool correctly.

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 tool takes zero parameters, so there are no parameter semantics to explain. The description does not need to compensate for missing input schema documentation, and the baseline for a no-parameter tool is appropriate here.

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?

Starts with a specific verb and resource: 'List named login identities (the multi-account layer)'. It then enumerates the exact metadata scope, including fields like cookie domains, updated_at, and account_verify verdict, making it clearly distinguishable from related account tools.

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?

Provides explicit usage context: 'Use to see which identities exist before session_create {account} picks one.' This tells the agent when to call it, though it does not state when not to use it or name alternative listing tools.

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