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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read-only nature is covered. The description adds the meaningful 'retry-eligible failed posts' filter, but does not discuss pagination or how 'failed' is defined.

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 a single short sentence with no filler. It front-loads the action and includes essential scoping information ('failed posts' and 'that can be retried') without 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 read-only list tool with zero required parameters, a documented limit, and an output schema present, this description is sufficient for correct invocation. It does not explain failure status scope or pagination behavior, but those are minor given the tool's simplicity.

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 only parameter, limit, is already fully documented in the schema with its default value. The description adds no additional meaning about the limit parameter, so the baseline score of 3 is appropriate.

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 states a specific verb ('List') and resource ('failed posts'), and adds the eligibility qualifier 'that can be retried.' This distinguishes it clearly from broader tools like posts_list and from retry actions like posts_retry or posts_retry_all_failed.

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 'that can be retried' gives useful context about what subset is returned, implying it is useful for inspecting retry candidates. However, it provides no explicit guidance about when to prefer this tool over other list/retry sibling tools.

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