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

Annotations already declare non-readonly, idempotent, non-destructive, closed-world semantics, so the bar is lower. The description still adds real value beyond them: the required profile:write scope, the fact that this is a full replacement, and the exclusion of wallet/identity/payment concerns. It omits validation-failure behavior, which keeps it out of 5 territory.

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?

Three tight sentences: purpose first, then the scope prerequisite, then the boundary exclusions. Every sentence carries information an agent needs before calling, and nothing is repeated from the schema or 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 single-parameter mutation with no output schema, the description covers purpose, auth requirement, replacement semantics, and scope exclusions, which is enough to call it correctly. The only gap is what happens on invalid handles/links or rejected scope, which an agent might want to anticipate.

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 description coverage is 100% and the nested schema description already spells out 'Complete replacement; empty text clears a field' along with link constraints, so the schema carries the load. The description's field list (display name, handle, bio/purpose, links) mirrors the schema without adding format or syntax detail, landing at the baseline 3.

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 ('Replace the verified key owner's private display name, handle, one-line bio/purpose and links') and enumerates exactly which fields are affected. It is unambiguous against profile_read / profile_identities_read by virtue of the update verb, but it never names a sibling explicitly, so it stops short of full differentiation.

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?

Gives a clear precondition ('Requires explicit profile:write scope') and draws explicit boundaries ('No wallet selector or identity verification; no payment/history changes'), which tells the agent when this tool is and is not the right call. It does not, however, point to profile_read as the alternative for read-only needs.

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