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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data. The description adds real context by disclosing that the response includes contact_list_ids (the lists keyword texters are added to) and the underlying REST route. It says nothing about auth requirements, rate limits, or error behavior, but the bar is lower given the read-only annotation.

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 tight sentence plus the endpoint route; nothing is wasted and the essential information is front-loaded. The endpoint path is mildly redundant for an agent but useful metadata, so slightly below a perfect score.

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 response, and it does so only partially by naming contact_list_ids while leaving the rest of the keyword object's fields unspecified. For a trivial get-by-id tool this is adequate but not thorough.

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 parameter is fully described in the schema as a positive integer id. The description only adds 'by id,' which is no meaning beyond what the schema already states, so the baseline 3 applies.

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 names a specific verb and resource ('Get one keyword by id') and clarifies the singular scope, which implicitly separates it from the sibling list_keywords. It also previews one returned field (contact_list_ids), so the agent knows what it gets back. It stops short of an explicit sibling contrast, but the purpose is unmistakable.

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 only implied: 'by id' tells the agent it needs a keyword id in hand, which suggests using this after enumeration rather than as an entry point. There is no explicit when-to-use/when-not guidance and no mention of the list_keywords alternative for discovery.

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