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

Beyond the readOnly/idempotent/non-destructive annotations, it discloses two non-obvious behaviors: an empty context is returned when nothing is known and is not an error needing comment, and the tool requires Keeploop Pro. These are exactly the kind of edge-case and auth/plan facts annotations do not carry.

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?

Front-loads purpose, then usage, composition, edge case, and requirement in a tight sequence. Every sentence carries distinct information with no repetition.

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?

With an output schema present, return format need not be detailed, and the description still frames the output (context block) plus the empty-return case. Combined with the usage trigger and Pro requirement, an agent has everything needed to call it correctly.

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 0%, so the description must carry the burden, and it only partially does: 'to' is implied as the recipient/company and 'sender' as the account, but neither is defined (e.g. email address vs name) and format is unspecified. It adds conceptual hints but not enough to fully substitute for the missing schema descriptions.

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+resource (get the user's writing voice) and clarifies the return shape (a ready-to-use context block). It also describes what the profile is composed of (general account voice, recipient/company-specific voice, real past examples), which lets an agent distinguish it from siblings like save_draft or send_email.

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?

Gives an explicit, prescriptive trigger: 'CALL THIS BEFORE DRAFTING any email you intend for the user to send, then write the draft in the voice it describes.' That is strong when-to-use guidance, though it offers no when-not-to-use or named alternatives.

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