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

Annotations already declare readOnly/idempotent/no-destruct, so the bar is for added context, and the description delivers: price and stock are read live on every call, unknown or discontinued ids return an error instead of a guess, and accepted id forms/case-insensitivity are spelled out. These are traits the annotations cannot convey.

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 usage condition, then the id contract, then failure behavior, then the sibling pointer. Every sentence carries distinct, actionable information with no restatement of the name or title.

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 single-parameter read tool with an output schema (which needn't be described), the definition covers trigger, accepted id formats, failure semantics, data freshness, and sibling routing. Nothing needed 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 coverage is 100% (baseline 3), but the description goes well beyond the schema's 'id from find_products or a product link' by adding numeric product id, barcode, any letter case, and the crucial negative rule that a product name does not work. That materially changes how an agent constructs the argument.

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+resource ('get_product' -> full product details) and enumerates the conceptual fields it exposes (brewing, caffeine, taste, ingredients, allergy advice). It also names the sibling it is not by routing side-by-side viewing to compare_products, so an agent can distinguish it without opening schemas.

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?

Explicit trigger ('when someone asks how to brew ... or wants its full details') plus concrete alternatives: find_products for name search and compare_products for comparison. It also states when it will fail (name does not work, unknown/retired id errors) rather than silently guessing.

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