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

Goes well past the annotations: discloses privacy ("no sender is told"), cost ("Free"), a prerequisite ("Needs a hosted identity (create_identity)"), and a return hint ("Returns data.waiting"). "open to undo" clarifies reversibility, consistent with idempotentHint=true and destructiveHint=false.

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 action and its benefit lead the sentence and no sentence is filler. The middle clause is dense with colon-delimited fragments, which is efficient but slightly harder to parse than distinct sentences would 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?

Covers the action, the privacy and cost model, the identity prerequisite, and points at the returned data.waiting (output schema carries the rest). For a two-parameter mutation tool, nothing an agent needs before calling it 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?

Schema coverage is 100% and the description's phrasing for both parameters (entry/message ids; the five state values) duplicates the schema text almost verbatim. It adds no syntax, batching, or state-transition detail beyond what the schema already provides, so 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?

States a specific verb and resource: "Mark items of your own inbox done, so they stop waiting", with the inputs named inline. It implicitly separates itself from mark_updates_read (read status vs. closure) but never names that sibling explicitly, leaving the distinction to be inferred.

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?

"Replying to a message, accepting or declining a request and a verdict on work you review mark it for you" tells the agent when this call is unnecessary, which is genuinely useful routing guidance. It lacks an explicit statement of the inverse (call this when you have not acted through those flows, and not for mere read-marking).

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