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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds the REST path, which reveals that the account scope comes from context rather than a parameter, but says nothing about error behavior (e.g. unknown template id) or response shape.

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 very short, front-loaded fragments with no filler. The raw endpoint path is mildly redundant with the tool's purpose but does clarify scope; nothing is bloated.

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 simple one-parameter read with no output schema, the definition is minimally sufficient, but it leaves the agent guessing what a template object contains and how failures surface. The structured annotations carry the safety profile, so the remaining gap is modest rather than critical.

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% and the single parameter template_id is documented in the schema, so the description adds no parameter meaning beyond it. Not that it needs to add much for a one-param lookup, but it does not explain id format or source.

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+resource: fetches one message template identified by id, which implicitly distinguishes it from the sibling list_templates. It does not explicitly name that sibling, but the 'one ... by id' phrasing makes the single-item scope unambiguous.

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: an agent can infer this is the single-template lookup versus list_templates, but there is no explicit when-to-use statement or precondition, such as needing a template_id obtained from the list call.

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