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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The description adds value by explaining the meaning of 'enabled' in terms of reporting capabilities and by disclosing the PLATFORM_DISABLED failure mode for cross-platform tools. This is behavioral context beyond the annotations, with no contradiction.

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?

Three sentences with no wasted words. The core purpose is front-loaded in the first sentence, the second explains the enabled flag, and the third connects the tool to cross-platform behavior. Every sentence earns its place and the length is proportionate to the tool's simplicity.

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 is fully adequate for a zero-parameter, read-only listing tool. It covers what is listed (platforms), the additional attribute (enabled status), and why that matters for cross-platform tool usage. An output schema exists to provide structural details, so nothing critical 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?

The tool has zero parameters and schema coverage is 100%, so the description carries no parameter-documentation burden. It still adds relevant context by mentioning that cross-platform tools take an optional platform argument, which indirectly explains why platform discovery matters. Baseline 4 for zero-parameter tools is appropriate.

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 uses a specific verb and resource: 'List every prediction-market platform this server knows about and whether it is enabled.' This clearly distinguishes it from sibling list tools like list_events, list_sports_markets, and list_tags, which focus on different entity types.

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 explains the practical context: enabled platforms report their market-data and trading capabilities, and cross-platform tools accept an optional platform argument where disabled platforms fail with PLATFORM_DISABLED. This tells an agent why and when to call list_platforms (to discover platforms and their enabled status). It stops short of explicitly saying 'use this when X, use sibling Y when Z,' but the usage context is strong.

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