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

With no annotations, the description must carry the behavioral burden. 'Look up' implies a read operation and 'Free' discloses cost behavior, which is useful. But it does not explicitly state that no mutation occurs, nor does it mention auth requirements, rate limits, or failure 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?

One compact sentence that front-loads the action and resource, uses a colon to introduce the output fields, and ends with the cost qualifier 'Free'. Every clause earns its place; there is no redundancy or filler.

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 single-parameter lookup with no output schema, the description adequately captures the accepted input, the returned data categories, and cost. Minor gaps remain around error responses and invalid-ref behavior, but they are not critical for an agent to select and invoke the tool.

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?

The input schema already fully documents the single parameter, including the agentId-as-number and 12-character slug alternatives. The description only restates 'by agentId or draft slug' without adding new format or usage nuance, so it provides no meaningful semantic value beyond the schema.

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 action ('Look up an Arc Agent Passport'), the resource, and the accepted reference formats. The colon-separated list of returned fields makes the tool's scope concrete and distinguishes it from transaction-oriented siblings like arc_passport_buy or arc_passport_draft.

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 clearly implies the use case: retrieve passport status by ref. However, it does not explicitly say when to prefer this over alternatives such as arc_agent_status or arc_passport_draft, nor does it mention exclusions or prerequisites.

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