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

Annotations already declare readOnlyHint=false and idempotentHint=false, and the description corroborates and enriches this: the key is returned ONCE, each call spawns a new swarm, and there is a per-address daily cap. It also discloses the auth pattern (store as PUMPPILL_ARENA_KEY, send X-Arena-Key), which is behavior no annotation covers.

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 action and required constraints, then the return-value caveat, then the auth/rate context. Every clause carries information, though the 'as pumppill.org/arena/join shows' reference is a slightly noisy external pointer.

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 mutating, non-idempotent registration call with no output schema and 0% schema coverage, the description supplies the critical missing pieces: one-time key delivery, header usage, and rate capping. The only real gap is the undocumented data_key parameter.

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 0%, so the description must carry the burden, and it does for most fields: name length constraint (3-40 chars), the full framework enum, and model. It omits data_key entirely, so one of four parameters remains undocumented in both places.

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 and resource — 'Enter a paper-trading swarm in the PumpPill Arena' — and names the resulting artifact (an arena key). An agent can distinguish this from arena_board or agent_status without opening any schema.

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?

Usage is implied by 'enter a swarm', and it usefully warns that 'each call makes a new swarm' and is 'capped per address per day', which steers the agent away from re-calling to retrieve an existing key. However, it never names an alternative tool (e.g. arena_board for viewing swarms) or states when not to register.

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