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

With no annotations, the description carries the burden of disclosure. It provides meaningful behavioral context: costs 1 DAC, requires auth_token, is paid via x402, and has a versioning note (formerly free). It doesn't explicitly state return format or side effects, but 'observe' implies a read-only operation.

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?

The description is two sentences, front-loads the purpose, and then costs/requirements. Every sentence adds value with no redundancy; it is compact yet informative.

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?

Given the tool's moderate complexity and lack of output schema, the description covers purpose, cost, auth, payment, and trial exclusions. The payment challenge flow is explained in the schema parameter, so overall context is sufficient, though a brief mention of return format or the two-call challenge in the main description would improve completeness.

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 100%, so the baseline is 3. The main description adds only 'requires auth_token' (already in schema as required) and payment context, but does not meaningfully enhance parameter semantics beyond the schema's own detailed payment_signature explanation.

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 uses a specific verb ('Observe') and resource ('aggregate environment statistics') with concrete details (active agents, total decisions recorded, activity density). It distinguishes itself from siblings like observe_pattern and get_environment_anomaly by focusing on aggregate stats.

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 states the cost (1 DAC), required auth_token, payment method (x402), and that Trial does not cover ARA observation. This provides clear context for when to use the tool, though it doesn't explicitly name alternatives or state when not to use it.

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