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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful context beyond them: the cost ($0.01 or a RobinX plan key), the ranking methodology and why a 3-of-4 record ranks below 10-of-19, the evidence-label grading, and the fact that the governing rules are returned in the response.

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 core definition is front-loaded in the first sentence, with methodology, output fields, and pricing following in a logical order. It is dense and the parenthetical pricing clause is somewhat run-on, but no sentence is wasted.

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 compensates by enumerating the returned fields (rank_score, early_rate, median 1h move, graded-call count, evidence label, rules) and disclosing cost. Combined with annotations covering the read-only/open-world profile, an agent has enough to decide and call it; only the sibling-level routing against robinx_leaderboard is unaddressed.

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 the schema-description baseline is 4 and there is no parameter semantics to explain. The description does not misrepresent any input, though it also cannot add anything 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?

The description gives a specific verb+resource: an X caller leaderboard for Robinhood Chain, with the ranking metric (rank_score, the 95% Wilson lower bound) spelled out. It is clearly distinct in content from robinx_caller/robinx_caller_calls, but it never explicitly states how it differs from the sibling robinx_leaderboard, so it falls short of full sibling differentiation.

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 is only implied. 'Measured, not follower count' hints that this is the credibility-weighted alternative to a follower-based ranking, and the pricing note implies a cost decision, but there is no explicit when-to-use, when-not-to-use, or named alternative tool.

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