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

Annotations already declare readOnlyHint=true, openWorldHint=false, and idempotentHint=true. The description adds valuable behavioral context by stating it surfaces timing conflicts and explicitly guarantees it will not invent missing facts, which goes beyond annotation coverage and addresses potential hallucination risks.

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?

The description is a single, front-loaded sentence with zero filler. 'Compare 2–6 current public guide items and surface timing conflicts without inventing missing facts' efficiently conveys action, scope, and a key constraint in under 20 words.

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?

Given the presence of an output schema (which presumably describes the conflict results), the description need not explain return values. It adequately covers the tool's inputs (items) and behavior (timing conflicts). Minor gap: it doesn't specify whether items must be events/sessions or any type, though types are provided in the schema, and it doesn't mention edge cases (e.g., no conflicts). Overall, sufficiently complete for a low-complexity comparison tool.

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 only 33% (only 'query' has a description), so the description must compensate. It clarifies the 'items' parameter by describing them as '2–6 current public guide items' and ties their use to timing conflict detection, but it does not explain 'goal' or the exact format of 'items' beyond count and type. Partial compensation, not complete.

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 states a specific action ('compare') and resource ('current public guide items'), and narrows the purpose to 'surface timing conflicts'. It also adds a behavioral constraint ('without inventing missing facts'), making the tool's intent unmistakable and distinct from planning or search siblings.

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 implies usage (comparing guide items to find timing conflicts) but does not explicitly state when to use this tool versus alternatives like plan_day or get_guide_item. It provides no exclusions or explicit alternative references, so an agent must infer the appropriate context.

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