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

Annotations only declare the generic safety profile (destructive, non-idempotent, not read-only); the description adds substantial context: consent semantics, the fresh single-use nonce requirement, the both-parties-must-sign activation rule, broker key custody, and concrete 403/404 failure codes. Everything is consistent with the annotations, so no contradiction arises.

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?

The verb+resource purpose is front-loaded and each sentence carries distinct information (mechanism, activation, custody, errors, legacy name) with no filler. It is dense with em-dash clauses rather than sprawling, though the many stacked facts slightly crowd the opening.

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 mutation tool with no output schema, the description covers the essential unknowns: what triggers activation, that the nonce is single-use, who can sign, what error codes to expect, and backward-compatible naming. An agent has everything needed to invoke it 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% with all four parameters fully documented, so the schema carries the load and the baseline is 3. The description adds only marginal meaning by tying the signature to membership_statement and the nonce freshness, but gives no extra syntax or format detail beyond the schema.

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 (sign) and resource (a membership's exact terms) plus its mechanical definition: an Ed25519 signature over membership_statement for a fresh single-use nonce. It distinguishes itself from nearby siblings (propose_membership, terminate_membership) and disambiguates the legacy sign_contract name, which an agent can resolve 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?

The description implies the usage context — you sign the terms so the membership can become active once both parties have signed — and clarifies the old sign_contract name for routing. However, it never states when to use this over propose_membership or when signing is not appropriate, leaving the alternative selection to inference.

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