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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety and stability profile is covered. The description adds one real piece of context beyond that: the returned identity is 'opaque' (not a human-readable PII value like an email), which tells the agent not to expect usable profile fields. Still thin on what the caller actually receives.

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 short sentences, front-loaded with the action and result, with the 'no email required' qualifier placed immediately after. Nothing is padded or redundant.

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?

An output schema exists, so return-value detail need not be in the description, and a no-arg read tool is inherently simple. The description is close to sufficient, though a one-clause note on when to prefer it over the brand/workspace context tools would make routing unambiguous.

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?

The tool takes zero parameters, so the schema carries no semantic burden and the baseline for a no-param tool applies. Nothing in the description is needed to explain parameter usage.

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 ('Return a stable opaque identity for this authenticated account'), which is clearly distinct from a profile-mutation tool like update_brand_profile. However, with ~65 siblings including discover_brand_profile, get_brand_context, and get_workspace_capabilities, it never explicitly distinguishes itself from those identity/profile-adjacent tools.

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 phrase 'No email required' implies the useful context that this is the cheap identity lookup that avoids an email-based flow, but there is no explicit when-to-use, when-not, or named alternative (e.g., discover_brand_profile). Usage is only implied.

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