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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add context — and it does, disclosing that the return is full Markdown text and that ids come in two prefixed forms (guide:<slug>, code:<code>) or as an fxlayerhq.com address. It stops short of describing error behavior for malformed ids.

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?

A single front-loaded sentence that leads with the return value and then qualifies the id input. No filler; the parenthetical id formats earn their place.

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?

With no output schema, the description carries the burden of describing the return, and it does (full text in Markdown). For a one-parameter read tool with annotations covering safety, this is nearly complete; only failure modes and explicit sibling disambiguation are 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 0% — the schema only says the single parameter is a string. The description compensates well by explaining what the id is (returned by search) and its two concrete formats plus the address alternative, giving real meaning beyond the type declaration.

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 (read/return full text) and resource (a guide or a purpose-code page), plus the accepted id forms. It is clear on its own, though it never explicitly contrasts itself with the close sibling get_purpose_code, so an agent must infer the difference.

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 'by the id `search` returned' implies the intended workflow (call search first, then fetch the id), which is useful. However, there is no explicit when-to-use guidance and no comparison against get_purpose_code, find_purpose_codes, or search, so routing is only implied.

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