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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds two useful traits: it is a 24-hour trending window, and passing username+league excludes already-rostered players. The "Market data only" disclaimer hints at a scope boundary, but no rate limits, data freshness, or failure behavior (e.g., unknown username) are disclosed.

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?

Front-loaded with the user-facing trigger phrases and stays to two sentences with no filler. The nested quoting and em-dash clause make it slightly dense to parse, but nothing 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?

For a 4-param, all-optional read tool with no output schema, the description conveys the data source (Sleeper), the window (24h), and the second data source (Kalshi prices). Return shape is only gestured at, but annotations plus schema cover the rest.

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%, so limit, league, position, and sleeper_username are all documented already; the description largely restates those descriptions rather than adding format or edge-case detail. Baseline 3 applies when the schema carries the parameter burden.

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 concrete verb+resource: Sleeper's most-added players in the last 24 hours paired with Kalshi prices. The quoted user phrasings ("who is everyone adding off waivers") make the resource unambiguous and distinguish it from siblings like best_available or my_league.

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?

Gives clear invocation contexts via two quoted user intents and explains the optional narrowing path (position filter; username + league to see only available players). It does not name a sibling alternative or say when NOT to use it versus best_available, which keeps it below a 5.

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