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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds nothing beyond that – no note on what fields come back, whether a missing ID errors, or any auth/access scope. It is pure restatement.

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?

Short and front-loaded, but the two sentences are near-duplicates: 'Retrieve a post' and 'Fetch a single post by ID' convey the same fact. The second sentence only earns its place for the 'single/by ID' qualifier, so this is efficient but partly redundant.

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 one-parameter read tool whose annotations already cover the safety profile, the description is minimally sufficient. However, with no output schema, it gives no hint about the returned post shape or behavior when the ID does not resolve, leaving minor gaps.

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?

There is a single parameter with 100% schema description coverage ('Post ID', plus a pattern constraint), so the schema carries the full burden. The description says 'by ID' but adds no new meaning such as ID source or format. Baseline 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?

States a specific verb+resource combination: 'Retrieve a post' / 'Fetch a single post by ID.' The word 'single' plus the ID requirement implicitly separates it from listPosts, and the resource noun separates it from getStory/getVideo. It stops short of explicitly naming a sibling to contrast against.

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?

There is no statement of when to use this tool versus listPosts, getPostAnalytics, or the story/video getters. The only guidance is the implicit 'by ID' constraint, which comes from the schema, not the description.

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