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

Annotations already declare this is a non-read-only, idempotent, non-destructive write, so the safety profile is covered. The description adds the auth prerequisite (free SnoopScan key), which is genuine behavioral context, but says nothing about failure modes or whether marking is reversible.

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 tight sentences with zero filler, front-loading the action and its valid values before the prerequisite. Nothing extraneous and nothing 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?

For a simple two-parameter status update with an output schema and full annotation coverage, the description supplies the action, allowed values, and auth need. It stops short of explaining mentionId semantics or error behavior, but those are minor given the tool's low complexity.

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 0%, so the description must carry the parameter burden. It does enumerate the four valid status values (new, seen, irrelevant, done), which compensates for the missing status enum, but mentionId is left entirely unexplained in both schema and description.

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 (set) and resource (a mention's status) with the exact target field, so an agent knows precisely what changes. It is clearly distinct in intent from read-only siblings like listMentions or watchMentions, though it never names or contrasts those alternatives.

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?

The only guidance is a prerequisite ('Needs a free SnoopScan key'). There is no when-to-use vs when-not, and no routing to listMentions/watchMentions for the read side of the same resource, leaving the agent to infer usage context entirely.

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