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

With no annotations, the description carries the full burden. It discloses the key behavioral steps: validation of capability set and constraints, signing as witness (with specific OAI), storage, and return of the signed token. It also adds an important trust-model caveat: 'Sigil is the ATAP witness — there is no kernel observer.' This goes beyond a simple update statement, though it doesn't cover failure modes, idempotency, or permissions.

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 concise paragraphs, front-loaded with the core action, followed by a process summary and a relevant trust-model note. Every sentence adds value, and there's no fluff or repetition. The link provides additional reference without bloating the description.

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?

The tool is complex (7 parameters, nested objects, no output schema), and the description only covers the high-level flow. It doesn't explain the meaning of all parameters, expected formats, error scenarios, or the structure of the returned token. The low schema coverage means the description should fill these gaps, but it leaves too much to inference.

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 only 14%, so the description must compensate. It explains capabilities and constraints indirectly through the validation sentence, and mentions the profile example, but it leaves operator, agent_type, expires_at, and attestation_policy entirely unexplained. This is insufficient for a 7-parameter tool with nested objects.

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?

The description opens with a specific verb and resource: 'Registers an ATAP v0.1 AIT for a media-buying agent under the sigil:media_buyer:v1 profile.' This clearly states the action and scope, and the registration action is distinct from sibling tools like sigil_atap_ait_status and sigil_atap_witness. It fully answers what the tool does.

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 description provides clear context: it's for registering ATAP AITs when Sigil is the witness, validates capabilities/constraints, and returns a signed token. It doesn't explicitly mention when not to use it or name alternative tools, but the specialized nature and workflow context make the usage scenario clear. This is more than implied usage, though not fully explicit about exclusions.

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