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

With no annotations, the description carries the full burden and does well: it discloses the output destination (the client's 'Why this changed' screen), the required voice, and the idempotency-style constraint 'call this once.' It does not state whether the record can be overwritten, what permissions are required, or how failures behave, which keeps it out of 5 territory.

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 sentences, front-loaded with the purpose before the audience and timing guidance, and each sentence carries real information. It is slightly dense in the second sentence but nothing is 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?

For a write-oriented tool with no annotations, no output schema, and five parameters, the description supplies the essential context an agent needs: what to write, the tone, the audience, and the timing. Missing only edge behavior (re-invocation, error handling), which is a minor gap rather than a critical one.

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 80%, so the schema already explains math, inputs, changes, and headline in detail. The description's gloss ('what you looked at... the numbers behind it') loosely maps to inputs/changes/math but adds no per-parameter syntax or format detail beyond what the schema provides, so the baseline 3 is 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 names a specific verb ('Record') and a specific resource ('the coach-voice explanation of the AI Coach run'), and the phrase 'what you looked at, what you changed and why, and the numbers behind it' makes the payload's purpose unambiguous. No sibling tool in the list does anything similar, so an agent can identify this immediately.

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?

It gives explicit sequencing: 'Call this once, after you have created or adjusted their plans,' which ties the call to the create/update_diet_plan and create/update_workout_plan siblings without naming them. What is missing is an explicit exclusion or a named alternative, so it falls just short of a 5.

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