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

Annotations declare readOnlyHint=false and idempotentHint=true, and the description substantiates this by spelling out that the write path is 'name, change, or resend' rather than destruction. It goes well beyond the structured fields by disclosing the email-masking behavior ('address hidden in the middle'), the full set of read states, the confirmation/plan lifecycle, and that the call costs nothing.

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?

Four compact sentences, front-loaded with what the resource is before splitting into read/write modes. Every clause carries information (states, masking, plan trigger). Minor debt: 'a pass never waits for it' and 'Costs nothing' are terser than they are clarifying, but nothing is 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?

An output schema exists, so return shape need not be explained, yet the description still summarizes the possible read states. For a single-optional-parameter tool with annotations covering the safety profile, an agent has all it needs to invoke correctly. Only the jargon-y confirmation/pass interaction leaves a small interpretive gap.

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% and the single parameter is already documented, so the baseline is 3. The description adds semantics the schema does not: the same parameter can name the owner, change an existing value, or merely re-send a confirmation, and that omitting it is a read. That is real meaning beyond the schema's terse 'omit it to read'.

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?

Names a specific resource (the account owner) and precisely describes its dual behavior: a no-argument read versus an owner_email write/resend. It even enumerates the states the read returns (confirmed, unconfirmed, missing, removed), which most definitions omit. It is clear enough to distinguish from any sibling, though the phrasing 'by email' and the opening fragment make the first sentence slightly oblique.

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?

Explicitly states the selection condition between the two modes: no arguments reads state, owner_email names/changes/resends. No alternative tools are named, but none of the siblings overlap with owner management, so there is nothing to route away from. Prerequisite context (free plan starts on confirmation) is also given.

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