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

With no annotations, the description must carry the burden of behavioral disclosure. It does state the return value ('Returns all available plan options with monthly and total prices'), which is useful. However, it does not mention error behavior, whether data is real-time, or any authentication or rate limitations. This is adequate for a simple read-only tool but leaves some gaps.

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 concise sentences, front-loaded with the action and resource. It avoids fluff and every sentence provides useful information (what the tool gets and what it returns).

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 simple tool with one parameter and no output schema, the description is complete enough: it names the resource, the scope (Prelude NZ), and the output (plan options with prices). The schema covers the parameter format. The workflow is further clarified by the schema hint to use search-instruments. Minor missing details like currency or sample output are not critical for this tool's simplicity.

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 parameter description in the schema explains the format and gives an example ('student-violin'), and also directs the user to search-instruments for valid slugs, which adds semantic value. The main description adds no additional parameter insight, so a score of 3 is appropriate.

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 tool's purpose: 'Get rental pricing plans for a specific instrument at Prelude NZ.' It uses a specific verb ('Get') with a specific resource ('rental pricing plans'), and the mention of 'instrument' and 'Prelude NZ' distinguishes it from sibling tools like FAQs, instruments search, and teachers search.

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 implicitly conveys when to use the tool (when needing rental pricing for an instrument) and is clearly distinct from sibling tools. The parameter schema further guides the user to 'Use search-instruments first to find slugs,' providing context for the required workflow without explicitly naming the alternative in the main description.

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