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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context beyond the annotations: it is free, requires no wallet and no payment, and takes no arguments. That auth/cost disclosure is exactly the kind of extra context worth crediting.

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?

A single sentence, front-loaded with the [FREE] tag and the preview purpose, then the cost rationale and the no-argument/n0-payment guarantee. No sentence is wasted and nothing is buried.

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 zero-arg, annotation-rich preview tool with no output schema, the description tells the agent everything needed to invoke it: it is free, requires nothing, and returns a sample of the paid tool's shape. It could be slightly stronger by stating that no real data is returned or how the sample relates to live results, but it is complete for correct invocation.

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?

Zero parameters, so the schema carries no semantics to explain. The description correctly states 'no arguments needed', reinforcing what the empty schema shows. Baseline 4 applies for a parameterless tool with 100% coverage.

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 names the specific resource it previews (edgar_fulltext_search) and states its exact role: return a sample response so the agent can see the response shape. It implicitly distinguishes itself from the paid sibling by referencing the 0.02 USDC cost, so an agent can route correctly. It does not describe what the underlying EDGAR full-text search actually returns, but that is the paid tool's job.

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?

Usage context is clear: use this before paying to inspect the response shape. The paid alternative is identified by name and cost, giving the agent a decision basis. There is no explicit 'do not use if' or mention of the many other *_preview siblings, so it falls short of a full when/when-not statement.

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