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

Annotations already declare idempotentHint=true, destructiveHint=false, and readOnlyHint=false, so the mutation profile is clear. The description adds genuinely new context: the signing action name, the required payload shape, and the security warning 'Never send a private key'. It doesn't cover error behavior or what happens in partial-failure batches, keeping it below a 5.

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 short sentences, front-loaded with the action, then the payload variants, then the safety caveat. No filler and every sentence carries information an agent needs.

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 non-destructive, idempotent mutation with no output schema, the description covers the action, the two payload modes, the signing requirement, and the key-handling warning. Remaining gaps (the 100-id cap, error semantics, return value) are minor given the annotation coverage.

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 0%, so the description must compensate. It fully explains the only semantic parameter, ids (empty payload = all unread, array = specific ids), but says nothing about kind, nonce, timestamp, publicKey, or signature beyond implying they form a signed envelope. That's partial compensation for a 6-parameter schema.

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: marking the signed profile's notifications as read. An agent can distinguish this from read_notifications (a query) without opening the schema, though no sibling is named 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 description gives the two payload modes ({} for every unread row, {ids:[...]} for a subset), which is useful operational guidance. It does not state when to prefer this over read_notifications or what happens if the ids don't exist, so usage context is implied rather than explicit.

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