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

Annotations already cover readOnly/idempotent/non-destructive, but the description adds substantial behavioral context beyond that: error instead of signal on unanswered nodes, reserved never-served codes, and the advisory ACM-403 halt behavior with a link to the market's halts page. The only gap is that the meaning of codes like ACM-200 'on the register' is domain shorthand an outsider must infer.

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?

Every clause arguably earns its place, but the single semicolon-chained paragraph is dense and hard to parse, with code names interleaved with behavioral rules. It is front-loaded but not structured for scanning.

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 output schema, the description carries the burden of explaining return values, and it does so by enumerating codes plus the per-code page URL. What's still missing is the response payload shape (bare code string vs. structured object), which keeps it from a 5.

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 coverage is 100%, but the description goes well beyond it by explaining input edge cases: ambiguous bare tickers return candidates and require an exchange, and a GTIN is explicitly rejected with an alternative service named. That is meaningful semantics the schema does not carry.

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 states a specific verb+resource (fetch the ACM-68000 signal for a listed security in its home market) and enumerates the possible signal codes, so an agent knows what it gets back. It does not differentiate itself from siblings like resolve_issuer or list_nodes, which is why it stops short of a 5.

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?

It gives several reachable input conditions (bare multi-issuer ticker → candidates, GTIN → ACM-404 with a pointer to gtinfetch.ai, non-responding home node → error), which is real usage guidance. However, it never says when to prefer this tool over resolve_issuer or list_nodes, leaving sibling selection implicit.

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