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

Annotations only cover the safety/idempotency profile; the description adds real operational context the agent could not infer: it is free, the first save prompts sign-in and creates the account, the card then opens the plan page where week one begins, and weekly emails start Monday mornings. It does not describe what happens on a retry or the shape of the result, but the output schema covers returns, so this is strong.

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-loaded with the decision rule, then behavior, then exclusions, and nearly every sentence carries new information. A few clauses are dense and slightly run-on (e.g. the emailWeekly sentence), but there is no 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?

For a 12-parameter mutation with an output schema, the description covers the prerequisites (make_plan first), the auth/account side effect, the idempotency expectation via the schema, the downstream consequence (plan page opens, week one starts), and the exclusion case. Nothing an agent needs to call it correctly is missing.

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 100%, so the baseline is 3. The description adds one genuinely useful instruction beyond the schema – 'Send the answers make_plan used, so the saved plan is the one they saw' – plus extra color on emailWeekly timing, but most of the twelve parameters are left entirely to the 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 ('Saves the plan to their Almost Fire account') and ties the trigger to a named sibling's output ('a plan make_plan made'). An agent can distinguish this from make_plan and from update_session without opening a schema.

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 explicit when-to-use triggers (user wants to keep/save/start a plan, or presses Save on the card) and explicit when-not-to-use cases ('Do not use before make_plan has shown them a plan, or to change the plan of someone who already trains in Almost Fire'). Alternatives and exclusions are both named.

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