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

The description discloses persistence ('stored with the calendar') and limits ('text only', 'max 5 docs × 200KB'), going beyond the annotations. However, it does not address idempotency or what happens when a document with the same name is attached again, which would be useful given idempotentHint=false.

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 two sentences, front-loaded with the primary action, and every phrase adds value. No fluff, no repetition of schema or annotations.

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 tool with 4 parameters and an output schema, the description adequately covers the core purpose, persistence, and constraints. The gap is the lack of clarification on repeated attach behavior (overwrite vs duplicate), which could matter, but overall the context is sufficient for most use cases.

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?

The description adds meaning to 'content' by specifying it is text-only and giving examples (syllabus/curriculum, exam spec) and size limits. It also clarifies 'name' usage through examples. Schema descriptions cover 50% of parameters, but admin_token and calendar_id are self-explanatory from their names, and the description does not conflict with 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?

The description clearly states the action ('attach a supporting text document to a calendar') with specific examples (syllabus/curriculum, exam spec) and constraints (text only, max 5 docs × 200KB). This distinguishes it from siblings like read_document or create_calendar, which serve different purposes.

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 when to use it: when you need to store reference material for future sessions ('so any future session can read it when revising the plan'). It does not explicitly name alternatives or exclusions, but the context is strong enough to guide selection.

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