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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value by naming the returned content categories, but it does not explain aggregation window, freshness, or whether the key is sensitive beyond the schema's 'private key' note.

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?

A single front-loaded sentence that immediately states the resource and its contents, with zero preamble. The trailing example is largely redundant given the schema and is the only weak link.

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 no output schema, the description usefully compensates by listing the four result categories an agent will receive. For a low-complexity, single-parameter read tool with full annotations, this is close to sufficient; finer detail such as time window or return format is missing but not critical.

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% and there is a single documented parameter, so the baseline is 3. The inline example '{"key":"fbk_…"}' merely restates the schema and adds no semantic detail about the key's role or format beyond what is already declared.

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?

Names a specific read operation ('your mirror from what you logged') and enumerates the four content categories it returns: success rate, confidence calibration, recurring failure words, open plans. 'Mirror' is metaphorical, but the enumeration makes the resource concrete enough to distinguish it from write-side siblings like log_task_outcome.

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 phrase 'from what you logged' implies a prerequisite (prior logging) and the context of use, but the description never states when to choose this over similar-looking siblings such as check_reliability, nor any exclusions. Usage is only inferable, not instructed.

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