Attach Session Evidence (Optional)

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

Annotations only indicate a non-read-only mutation, so the description carries the burden of behavior. It adds valuable context: the artifact is durable, carries `caller_submitted_unverified` provenance, promotes nothing, and requires the petitioner's verified capability token. No contradiction with annotations, though it stops short of describing removal or overwrite behavior.

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 sentences deliver the core action, scope, provenance, and usage guidance without obvious padding. It is dense but well front-loaded, though the long middle sentence about provenance could be slightly streamlined.

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 7 parameters and no output schema, this description covers the why, when, and who well, but leaves parameter semantics and return behavior unaddressed. An agent can understand the tool's role, but may still struggle to craft a fully correct call without additional schema descriptions.

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%, yet the description never explains session_id, label, content, extension, content_type, or response_format. It only gestures at 'artifact' and provenance, leaving the agent to infer parameter meaning from names alone. The enums and defaults in the schema help, but the description does not compensate for the coverage gap.

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: attach one durable evidence artifact to an existing session, out of band from a review round. It explicitly contrasts itself with the routine `evidence` field and clarifies that this tool 'promotes nothing', distinguishing it from review-round evidence tooling.

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 instructs when to use it: for material that does not belong to a specific round, and to prefer the `evidence` field for the routine path. It also states the auth constraint that only the session's own petitioner may call it, so an agent knows when not to attempt it.

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