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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety is covered structurally. The description adds genuinely new context: this tool is free and serves as the pricing/discovery surface for the paid tools, which is exactly the kind of cost/role information annotations cannot convey.

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 dense fragments with zero waste. The cost signal ('Free.') is front-loaded before the payload description, which is the most decision-relevant fact for an agent choosing among paid siblings.

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 an output schema present, the return values (capabilities, prices, URLs) need not be spelled out in the description, and no parameters require explanation. What remains thin is routing guidance relative to the three sibling tools, which is the only real gap.

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 tool takes zero parameters, so there is no per-parameter semantics to document and the baseline for a no-param tool is 4. The description does not need to compensate for any schema coverage gap here.

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 (Return) and enumerates concrete resources: service capabilities, paid-tool prices, and discovery URLs. An agent can tell this is the metadata/discovery entry point, though it doesn't explicitly name the sibling tools it complements.

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 leading 'Free.' plus the mention of 'paid-tool prices' implies this is the discovery call to make before/instead of the paid siblings, but there is no explicit when-to-use or when-not statement naming shadowgraph_alpha or the others.

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