Get a Glongus listing

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

Annotations already declare readOnlyHint=true and openWorldHint=false; the description goes beyond them by confirming no auth is required and warning that photo_urls may be empty. It does not contradict the annotations. It still says nothing about error behavior for a missing id.

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?

Front-loads the core action and id scope in the first clause, then explains return fields. The buyer_fee_estimate explanation is slightly wordy but each clause carries information an agent would otherwise have to guess.

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?

There is no output schema, so the description must carry return-value semantics, and it does: price units (pence), condition, photo_urls emptiness, shipping vs collection-only, and the fee/total breakdown. Combined with 100% schema coverage and the no-auth note, an agent has what it needs to call and interpret the result.

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 single id parameter already carries a pattern and example, so the schema does the heavy lifting. The description's 'lst_…' hint and the field-level explanations are about the response, not the parameter, adding little parameter meaning beyond the schema.

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 listing by id'), and the id prefix 'lst_…' scopes it precisely. It implicitly distinguishes itself from search_listings by fetching a single listing rather than searching, but never names that sibling explicitly.

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: call this when you already have a listing id. It adds a useful prerequisite ('No auth needed') but gives no guidance on when not to use it or which sibling to reach for when you lack an id (search_listings).

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