mark_message_read

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

With no annotations provided, the description carries the full burden and does so: it discloses per-recipient semantics, that no acknowledgement is emitted, idempotent re-call behavior returning the original timestamp, and the exact return shape. These are exactly the traits an agent needs before invoking a mutation.

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?

Front-loaded with the purpose, which is good, but the Idempotency section restates the Notes bullet ('Safe to call multiple times; later calls return the original timestamp') almost verbatim. The Returns section is also partly redundant given a declared output schema.

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 message-state mutation the description covers behavior, the alternative tool, idempotency and return fields, and an output schema exists so return values need no further elaboration. The only real gap is the unexplained 'format' and 'registration_token' parameters.

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 description coverage is 0% across 5 parameters, so the description must compensate and largely does not. The worked example incidentally shows project_key, agent_name and message_id, but 'format' and 'registration_token' are never explained in either place, leaving required vs optional inputs ambiguous.

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 ('Mark ... as read') plus resource and scope ('a specific message ... for the given agent'), and explicitly distinguishes itself from the sibling acknowledge_message. An agent can tell exactly what this does 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?

Explicitly names the alternative tool and the condition that selects it: 'This does not send an acknowledgement; use acknowledge_message for that.' It also clarifies the per-recipient scoping so the agent knows which agent the read state applies to.

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