set_primary_profile

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

Annotations declare destructiveHint=true and readOnlyHint=false, and the description reinforces this by explaining exactly what is mutated: the previous primary profile is demoted to secondary. It also adds non-obvious access context (requires a Proof account, PROOF_API_KEY must be set and the server restarted, and start_login does not unlock this tool). It does not state whether the change is reversible or what happens if the target is already primary.

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 tight sentences lead with the action and its side effect before the access caveat, so the critical information is front-loaded. The ACCESS block is longer boilerplate but is genuinely actionable rather than filler.

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 annotations covering the safety profile and no output schema, the description covers purpose, side effect, and the authentication gate. It stops just short of completeness by omitting error conditions (e.g., invalid or unknown profile_id) and whether the prior primary must exist.

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?

There is a single parameter with 100% schema description coverage ('Profile ID to set as primary'), so the schema already carries the semantics. The description adds nothing about the ID format or provenance, which is the expected baseline when coverage is complete.

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 precise verb and resource ('Set a profile as the primary profile') and immediately names the observable effect (previous primary becomes secondary). The resource word 'profile' cleanly separates it from the sibling set_primary_email and set_primary_phone without needing to open 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?

No guidance on when to choose this over related profile tools such as update_profile, get_my_profile, or list_profiles, and no note on prerequisites like the profile having to exist or already being part of the account. The access note is an authentication prerequisite rather than a when-to-use rule.

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