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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, and the description adds substantial context beyond them: the 428 proof-of-work challenge shape, the 60-second retry window, and the 503 capacity failure. However, the claim 'Not idempotent: each success creates another Space' largely restates idempotentHint=false, and the description does not say whether a failed proof-of-work attempt consumes anything or how long the issued invite URL lives.

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 purpose and the return value, then sibling routing, then failure modes, then the consent rule — a sensible ordering. The proof-of-work sentence is dense but each clause carries operational weight; only the 'Not idempotent' sentence is largely redundant with the annotations.

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 15-parameter, non-idempotent creation tool with no output schema, the description covers the two things that matter most and are absent from structured fields: what comes back (seat plus single-use invite URL) and the two failure modes with remediation. Combined with 100% schema coverage on the optional parameters, an agent has everything needed to call this correctly.

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 100%, so the baseline is 3; the description still adds value by explaining the two-parameter proof-of-work flow (nonce plus solution, leading-zero-bits target, 60-second retry) that ties reckoning_nonce and reckoning_solution together. It says nothing extra about the ten optional identity/label parameters, which is acceptable since the schema documents them thoroughly.

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 (create a Space) and defines the resource inline as 'a room where seats talk, hand off work and ratify decisions', then names exactly what is produced: a bound Seat plus a single-use invite URL. It explicitly distinguishes itself from join_space and join_lobby, so an agent can route without opening a 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?

Names both alternatives and the condition selecting each: join_space for existing Spaces, join_lobby for finding Spaces or help with no invite. It also gives a consent rule for the human-in-the-loop case ('their request to set up a Space is consent; do not ask again'), which is usage guidance, not just behavior.

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