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

With no annotations, the description carries the full burden. It discloses key behaviors: 'Persists across sessions,' 'Returns related knowledge,' and 'One insight per call.' It does not mention error handling or authorization, but these are minor for a memory-store tool.

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 well-structured with a clear flow: purpose, example, do/don't guidance, and constraints. It is longer than minimal but every sentence adds practical value, especially the examples.

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?

The tool has 3 parameters and no output schema. The description covers input format and content guidance thoroughly, but it only vaguely mentions 'Returns related knowledge' without describing the return structure. The durabilityDecision parameter is documented only in the schema, which is acceptable given 100% coverage.

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 the baseline is 3. The description adds value by providing a concrete JSON example and by guiding what the 'observation' should contain ('Store facts that help future sessions, not actions you took or bugs you fixed'). This goes beyond the schema's simple 'Write naturally'.

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: 'When you understand how something works — architecture, dependencies, module boundaries — store it here.' It identifies a specific verb (store) and resource (knowledge), and distinguishes itself from siblings with 'Catch-all for knowledge not covered by gotcha/convention.'

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 differentiates from gotcha/convention and provides strong usage guidance with wrong/right examples ('Wrong: “Fixed the null pointer in UserService.” Right: “UserService.getUser() returns null when session expires—callers must handle this.”'). It also states constraints like 'One insight per call' and persistence across sessions.

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