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

The description adds significant behavioral context beyond the annotations: it states that adding does not change publication status or URL, that inserting at a position shifts later articles down, and that it requires an API key. The annotations already indicate readOnlyHint=false, idempotentHint=true, and destructiveHint=false, and the description aligns with these. It could mention idempotency explicitly (e.g., what happens if called twice with the same position), but the existing disclosure is strong.

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 concise and well-structured: a clear first sentence stating the action, followed by short paragraphs covering prerequisites, identification method, position behavior, and error conditions. Every sentence adds value, and the information is front-loaded with the core purpose. No fluff or 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?

Given the tool's moderate complexity (3 params, no output schema, no nested objects), the description is complete: it covers prerequisites, identification, position behavior, side effects, and error conditions. The annotations provide safety hints (idempotent, non-destructive). It could mention the return value or success/failure response format, but with no output schema, the description's coverage is strong. A 4 is appropriate.

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 has 100% description coverage, so the baseline is 3. The description adds value by reinforcing the slug-based identification ('Not its title or id') and explaining the position semantics ('Omit to append at the end. Inserting shifts later articles down.'). It also clarifies the source of each slug (get_series, list_my_articles), which goes beyond the schema. This earns a 4.

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: 'Place an existing article into an existing series, optionally at a specific position.' It specifies the verb (place/add), the resource (article into series), and the key constraint (both must already exist). It distinguishes from siblings like create_series (which creates a series) and update_article (which modifies an article), making the purpose unambiguous.

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 explicit usage guidance: it states when to use (adding an existing article to an existing series), what not to do (it creates neither), and how to identify entities (by slug, not id, with references to get_series and article tools). It also explains the optional position parameter and the error condition for unknown slugs, giving clear context for when this tool is appropriate versus alternatives.

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