agent_mark_read_batch

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

With no annotations, the description carries the full burden and does well: it discloses the externally visible side effect ('senders can see when they were read'), the environment-variable gate, the default-off posture, and the identity under which it acts. It does not cover failure modes or partial-batch behavior, but the key behavioral risks are surfaced.

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?

Three tight sentences with no filler; the batch limit leads, followed by the visibility consequence and the authorization gate. Every sentence adds a distinct fact an agent needs.

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 one-parameter mutation with no annotations and no output schema, the description covers the operational gate, the side effect, and the identity. It does not explain what the call returns or how partial failures are reported, but that gap is modest given the tool's simplicity.

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% for the single message_ids parameter, so the baseline is 3. The description adds genuine meaning beyond the schema by imposing a 100-id ceiling on the array, a constraint absent from the schema itself.

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 ... messages as read') plus a concrete batch ceiling ('up to 100'), which implicitly distinguishes it from the singular sibling agent_mark_read. It never names that sibling explicitly, so the differentiation is inferred rather than stated.

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?

It gives a real precondition ('refused unless the human owner set VOIDLY_MCP_RELAY_ALLOW_STATE_CHANGES=1') and notes the feature is off by default, which is useful gating context. However, it never says when to prefer this batch tool over agent_mark_read or when a read-receipt side effect is undesirable, so usage is only implied.

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