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

With no annotations, the description carries the burden and does well on the two highest-risk behaviors: the confirm gate and the fact that meals REPLACES the entire list rather than merging. It is silent on permissions/ownership requirements and on whether the edit is reversible, which are meaningful gaps for a mutation tool.

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 tight sentences, front-loaded with the core operation, and the destructive replace warning is placed where it cannot be missed. No filler or repetition of the schema's structure.

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 7-parameter mutation tool with no annotations and no output schema, the description covers the confirm gate and meal replacement but leaves permission requirements, the effect on untouched fields, and four top-level parameters unaddressed. Adequate but not complete.

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 only 29% across 7 parameters. The description clarifies planId, the partial-update contract, and the replace semantics of meals — the most valuable additions — but says nothing about title, startDate, endDate, or description, and its enumeration of meal sub-fields largely restates the schema. Partial compensation for a low-coverage 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 ('Edit an existing diet plan') and scopes it to existing plans, which cleanly separates it from create_diet_plan, delete_diet_plan, and update_diet_plan_template in the sibling list. An agent can identify the operation without opening the 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 clear operational guidance: pass planId plus only the fields to change, and send the full meal list if meals is supplied. It does not name an explicit alternative for template edits (update_diet_plan_template) or state prerequisites, so it stops short of full when/when-not routing.

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