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

Annotations declare idempotentHint=true, readOnlyHint=false, destructiveHint=false. The description adds context beyond annotations: key-value scoping by identifier, retention policy (24h anonymous vs persistent authenticated), and cross-session persistence. No contradictions, though it doesn't explicitly address overwriting behavior, which is partially covered by the idempotent hint.

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 sentences, tightly written, front-loaded with the primary action, includes usage signals and companion tools. Every sentence earns its place with no fluff or redundancy.

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 key-value write tool with full schema coverage and informative annotations, the description covers purpose, usage context, persistence, scope, and companion tools. Nothing critical 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?

Input schema covers 100% of parameters with descriptive examples. The description adds semantic context that the key is scoped by the agent's identifier, which informs how to construct keys, and clarifies the value is any free-form text. This goes beyond the schema, but the extra value is modest given the schema already provides good guidance.

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 opens with a specific verb+resource ('Save data the agent will need to reuse later') and clearly distinguishes from sibling tools by explicitly naming recall and forget for retrieval and deletion. It also clarifies cross-session scope, making the purpose unambiguous.

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?

Provides explicit when-to-use guidance: 'Use when you discover something worth carrying forward' with concrete examples. Also tells when not to use by pointing to recall/forget as the retrieval/deletion counterparts, giving clear alternatives.

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