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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds a genuinely useful, non-obvious behavior: values above ~8k chars are truncated and flagged via truncated=true, which affects how an agent should interpret the result.

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?

Two short sentences, front-loaded with the core action and immediately followed by the truncation caveat. No filler.

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?

With an output schema present, the description needn't explain return shape, and the truncation note covers the main interpretation pitfall. The remaining gap is the discovery path (keys and namespaces must come from the sibling list tools), which an agent would need to infer.

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%, so all seven parameters (including account routing fields and context_id) are documented in the schema itself. The description mentions only 'by key' and adds nothing about namespaceId, accountId, zoneOrId or routing precedence, so the baseline 3 applies.

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 and resource ('Read a single KV value by key'), which an agent can map directly onto cf_kv_keys_list and cf_kv_namespaces_list without ambiguity. It does not explicitly name those siblings to differentiate, keeping it just short of a 5.

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?

No guidance on when to use this versus cf_kv_keys_list (key discovery) or how to obtain a namespaceId. The description gives a precondition-free read recipe but never says what to do first or when not to call it.

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