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

Annotations already declare readOnlyHint=true, so the description's job is to add context. It does so by clarifying the authorSource semantics, explicitly stating it reports where the byline came from and not that it is verified or correct. It also discloses that it resolves from two stores (database and MDX). This goes beyond the annotation without contradicting it.

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 moderately long but every sentence adds value. It front-loads the core purpose, then details resolution behavior, return fields, and clarifies the authorSource semantics. It is well-structured and avoids redundancy, though it could be tightened by trimming the explanation of return fields (which are self-explanatory).

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 single-parameter get tool with a read-only annotation and no output schema, the description is quite complete. It lists all return fields and explains the ambiguous authorSource field. It does not cover error cases (e.g., not found) or authentication, but these are minor for a straightforward retrieval tool and not critical for correct invocation.

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 schema already describes the id parameter as 'DynamoDB id or slug' with 100% coverage. The description adds the nuance that the id resolves across both the database and MDX stores, which is not fully explicit in the schema. This extra context helps the agent understand the dual-store behavior, raising it above the baseline for fully covered schemas.

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 (Retrieve) and resource (blog post), and explicitly distinguishes itself from search_blog_posts by noting it resolves IDs from both stores and that any ID from search_blog_posts will resolve here. This makes its purpose unambiguous and clearly separates it from siblings.

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 provides clear context on when to use this tool: when you have a specific ID or slug from search_blog_posts. It directly says 'any id search_blog_posts returns will resolve here', which is a concrete pointer. However, it does not explicitly mention when to prefer alternatives like browse_archive or get_related, so it stops short of full when-to-use/when-not-to-use guidance.

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