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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description goes beyond annotations by detailing the not-found error behavior for missing keys or expired TTLs, adding valuable runtime context that the annotations do not provide.

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 concise sentences accomplish everything: state the purpose, describe the return/error behavior, and provide usage guidance. There is no redundancy or filler, and the content is front-loaded with the core action.

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: it covers what the tool does, what it returns, what happens on failure, and how to discover keys when needed. Nothing essential 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?

The input schema provides 100% coverage for the single 'key' parameter with a clear description ('Exact key to look up (case-sensitive)'). The description's mention of 'by exact key' and case-sensitivity adds minimal value beyond what the schema already states. Baseline 3 is appropriate because the schema fully documents the parameter.

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 starts with a specific verb ('Read') and resource ('project's key-value store') with a clear scope ('by exact key'). It distinguishes itself from siblings like scalix_kv_list (key discovery) and scalix_kv_set (write) by explicitly focusing on single-key reads.

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 explicitly names scalix_kv_list as the alternative for discovering keys by prefix, giving clear guidance on when to use this tool instead. It also conveys the expected behavior for missing/expired keys, further contextualizing appropriate use.

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