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

Annotations already declare readOnlyHint=true, and the description adds useful behavioral context: the tool returns 154 fixed gaps, requires no key or email, has a Pro layer, and focuses on platform-specific ADP discrepancies. It does not describe the output shape in detail, but for a zero-parameter read-only tool this is a reasonable level of disclosure.

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 purpose is front-loaded in the first sentence, and the example and use-case list earn their place. It is slightly wordy with the 'Pro adds the judgment layer' and 'FREE' access details, but overall every section contributes actionable context and the description remains compact.

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?

The description conveys the data source, use cases, access requirements, and row count, which is strong for a zero-parameter read-only tool. However, there is no output schema and the description never specifies the exact fields returned beyond an illustrative rank example, and the unsupported filter claim leaves a gap in invocation correctness.

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 input schema has zero properties, so the baseline would normally be 4. However, the description advertises 'Filter by position (QB/RB/WR/TE/FLEX)' even though no filter parameter exists in the schema. This is misleading: an agent may attempt to pass an unsupported position argument and fail schema validation.

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 opens with a specific verb and resource: 'Find the 2026 fantasy players whose Average Draft Position swings most between platforms.' It names the exact platforms and gives a concrete example, making the tool's unique ADP-arbitrage purpose unmistakable and clearly distinct from sibling tools like compare_players or scan_mispricings.

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?

The description gives explicit use cases ('Use for ADP differences by platform', 'ADP arbitrage', 'who falls on ESPN vs Sleeper') and context about access ('All 154 gaps are FREE — no key, no email'). It does not state when not to use it or name alternatives, but the context is clear enough for an agent to select it in the intended scenarios.

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