mark_mail

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds the useful nuance that flagging accepts an optional colour and that the operations are paired inverses ('set or clear'), which reinforces reversibility, but it says nothing about batch failure behavior or partial application across ids.

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 front-loaded sentence with no filler; the parenthetical cleanly scopes the colour to the flag operation. Nothing is wasted or buried.

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?

With an output schema present and annotations covering safety and idempotency, the description supplies enough to call the tool correctly. The one gap is that the 1-500 id limit and expected response shape live only in structured fields, which is acceptable given the schema richness.

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%, so all three parameters are already documented; baseline is 3. The description's only added meaning is tying colour to the flag action and signalling its optionality, which the schema largely already conveys.

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?

Uses a specific verb ('Mark') with the resource ('messages') and enumerates all four supported states (read, unread, flag, unflag) plus the optional colour. An agent can distinguish this state-toggle tool from siblings like read_mail (reads content) or move_mail 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?

Usage is only implied: the description makes clear it is a state-changing batch tool, but it never states when to prefer it over alternatives (e.g. read_mail) or any preconditions such as ownership or folder scope. Adequate for a self-evident toggle, but no explicit when/when-not guidance.

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