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 genuinely useful behavior: it returns the complete field set in a single call and returns an error with suggested ids for unknown ids, which tells the agent how failure manifests.

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?

Two front-loaded sentences that state the operation first and details second. The long enumeration of returned fields is somewhat redundant given an output schema exists, but it does not obscure the core instruction.

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 single-parameter read with full annotations and an output schema, the description covers the identifier format, the success shape, and the failure mode. Nothing needed to invoke or interpret the call is missing.

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 the pattern plus maxLength fully constrain the single id parameter, so the schema does the heavy lifting. The description reinforces it with a kebab-case example ('model-context-protocol') but adds no semantics beyond the schema's own description.

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 and resource ('Fetch one Index Agentica entry by its id') and pins the identifier format with a concrete example. It is clearly distinguishable from siblings like search (which finds ids), list_categories, and get_content.

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?

Usage is implied rather than stated: the id must come from a prior search, and the mention of an error with suggested ids hints at a recovery flow. It never explicitly says 'use search first' or contrasts itself with get_content, so the agent must infer the routing.

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