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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond them: the payload contents and that the call is free (no cost/quota concern), plus "full" signals no filtering or pagination. It does not state response size or ordering, which keeps it from a 5.

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 short sentences: the first front-loads what is returned, the second gives the usage condition plus cost. Nothing is redundant or padded.

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 no parameters, no output schema and a simple read-only annotation set, the description is nearly self-sufficient because it enumerates the returned fields. A brief note on catalog size or ordering would make it fully complete, but nothing needed to invoke the tool correctly is missing.

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 there are no semantics for the description to carry; baseline 4 applies. The schema is empty and the description correctly makes no attempt to describe inputs.

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+resource ("Return the full signal-api catalog") and enumerates what it contains: products, types, params, prices, descriptions. The sibling tools (get_signal, get_regime, list_assets) clearly cover different resources, so an agent can distinguish it, though no sibling is named explicitly.

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?

"Use when you need the complete product list or metadata" gives a clear triggering condition, and the word "complete" implies it is the unfiltered enumeration rather than a targeted lookup. No explicit when-not guidance or named alternative, but the context is unambiguous.

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