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

Annotations already declare this is a mutation (readOnlyHint=false) that is non-destructive and not open-world, so the safety profile is covered. The description adds useful context about the recovery-login purpose, but omits key behavior for a write tool: whether an existing recovery email is overwritten, whether the change is reversible, and what confirmation is returned.

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?

One sentence, front-loaded with the action and followed by the reason — no filler. It is slightly compressed in the parenthetical aside but every clause carries meaning.

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 one-parameter mutation with annotations present and no output schema, the description gives adequate purpose but leaves the overwrite/idempotency question and the post-call state unexplained. It is minimally complete, not fully so.

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 required parameter with 100% schema description coverage ('Human's email' with email format), so the schema already does the work. The description adds no format, validation, or uniqueness nuance beyond what the schema states, making the baseline 3 appropriate.

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?

The description states a specific verb and resource ('Attaches an email to the account') and immediately explains the effect ('so the human can log in on proxycove.com via Forgot password'). It is clearly distinguishable from siblings like link_telegram or get_credentials, though it never names an alternative explicitly.

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 rationale ('never lose the balance') implies when an agent should call it, but there is no explicit when-to-use trigger, no exclusion, and no pointer to a related sibling such as link_telegram for alternate recovery channels. Usage is inferable rather than stated.

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