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

readOnlyHint=true already declares the safe-read profile, so the safety burden is covered. The description adds useful scope context by enumerating what comes back (house rules, cancellation policy, door code, wifi), which helps the agent gauge sensitivity and payload size. It says nothing about permissions or rate limits, so with annotations present this sits at a solid 3.

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?

One front-loaded sentence naming the verb, key, and returned contents, plus a compact endpoint reference. No filler and nothing redundant.

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 correctly compensates by enumerating the returned fields, and the required listingId is unambiguous. Minor gaps around permissions or behavior for missing ids keep it from a 5.

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 description coverage is 100%, so both listingId and includeResources are already documented in the schema, and the description adds no syntax or semantics beyond that. Baseline 3 is appropriate when the schema carries the parameter burden.

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 ('Fetch') and resource ('a single listing by id') and immediately enumerates the returned fields, which clearly distinguishes it from hostaway_list_listings. An agent can tell the single-record lookup apart from the list operation without opening either schema.

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 id' and the single-record framing imply when to use this over hostaway_list_listings, but no explicit when/when-not or alternative routing is stated. Usage is implied rather than prescribed.

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