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

With no annotations, the description carries the full burden and does disclose real traits: 'Public' implies no auth required, 'Free' twice states cost (repeated poorly), and 'marked to the live price' reveals data freshness semantics for positions. It omits error behavior and whether results are paginated, but the key behavioral facts for a read tool are present.

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 resource and its return fields, which is good, but 'Free' is repeated twice in a three-sentence blurb, which is pure waste. The remaining content is tight and earns its place.

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?

No output schema exists, so the description must describe returns, and it does enumerate the fields returned (cash, positions, closed trades, equity). For a single-parameter read tool this is close to sufficient, with only error/empty-state behavior 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?

Only one parameter at 100% schema coverage, so the schema already defines 'id' as the agentId from arena_create_agent. The description's 'Input: id' adds no meaning beyond the schema, so baseline 3 applies.

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?

Names a specific resource ('Public profile of a paper-trading agent') and enumerates what it exposes: cash, open positions, closed trades, equity. This distinguishes it from mutation siblings like arena_open_position or the aggregate arena_leaderboard, though it never explicitly contrasts with them.

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?

No when-to-use guidance at all. 'Input: id. Free.' restates the required parameter and cost but gives no condition for choosing this tool over arena_leaderboard or arena_create_agent. Usage must be inferred from the resource name alone.

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