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

Adds substantial context beyond the annotations: the operation is free, the server never receives private keys, and signing is ed25519 with base58 encoding over a canonical message. It also clarifies the upsert nature (submit *or* update). It stops short of disclosing rate limits, cutoff behavior at round close, or what a rejected signature does.

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?

Two dense sentences with the key incentive ('FREE') front-loaded, followed by the trust model and the signing procedure in execution order. No filler or repetition of the schema.

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 6-param mutation with no output schema, the description covers the critical preconditions (canonical message source, key custody, signature format). It omits what a successful submission returns and any timing constraint relative to round settlement, which an agent would still want.

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 83%, so the schema already documents roundId, wallet, price, signature and botName. The description adds genuine meaning for `signature` — that it is ed25519 base58 over the canonical message sourced from arena_rules/arena_current_round — which is not derivable from the schema alone.

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 specific verb pair (submit or update) and resource (signed BTC/ETH/SOL price prediction) scoped to the arena round, plus whether the round is current or supplied. This is unmistakable against siblings like arena_leaderboard or get_market_spots, which are read-only market/ranking tools.

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?

Explicitly tells the agent to sign the canonical message obtained from arena_rules / arena_current_round, which is a real prerequisite chain naming siblings. It does not state exclusions (e.g. whether updates are allowed after round close), so it falls short of a full when/when-not guide.

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