list_rules

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

No annotations are supplied, so the description carries the full burden, and it does add one genuinely useful fact: the required MailboxSettings.ReadWrite permission. However, it omits the return shape (no output schema), whether disabled rules are included, ordering, and whether the operation is read-only — the ReadWrite scope oddly suggests broader access than a list would need.

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 short sentences, front-loaded with the resource and scope, then the permission requirement. Every clause earns its place with no filler.

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 zero-parameter read tool with no output schema, the definition covers what is listed and the auth requirement, which is enough to invoke it correctly. The main residual gap is return-value expectations, which the absent output schema pushes onto the description.

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, which is the baseline-4 case. The description correctly implies a no-argument full listing and adds nothing misleading about inputs.

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?

Names a specific verb and resource ("List the inbox message rules") and disambiguates what "rules" means with a parenthetical definition ("server-side rules that run on incoming mail"). It is clearly distinct from create_rule and delete_rule by its read framing, though it never explicitly contrasts itself with them.

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?

Usage is only implied: an agent infers this is the tool to inspect existing rules, presumably before create_rule or delete_rule. There is no explicit when-to-use statement, no exclusions, and no mention of prerequisites beyond the permission note.

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