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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful scope ('including its routing rules') and the underlying API mapping, but says nothing about error behavior when the slug is missing, permissions, or rate limits.

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 tight sentences with the resource and lookup key front-loaded. The trailing 'Portkey: GET /configs/{slug}' endpoint mapping is mildly redundant but cheap and aids API correlation.

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 single-parameter read tool with no output schema, the description conveys the lookup key and return scope ('including its routing rules'). Minor gaps around not-found behavior, but nothing essential to correct invocation is 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?

With a single parameter at 100% schema description coverage, the schema already documents the slug/id input, so baseline 3 applies. The description's '(or id)' restates rather than extends the schema's 'config slug or id'.

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 states a specific verb and resource ('Get a single gateway config by slug (or id)') and clarifies what is returned ('including its routing rules'). It implicitly contrasts with the sibling list tool via 'single', but never names portkey_list_configs, so sibling differentiation is inferred rather than stated.

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 by the 'single config by slug' framing, which suggests this is the lookup path once a slug is known. However, there is no explicit when-to-use guidance, no statement of when to prefer it over portkey_list_configs, and no prerequisites mentioned.

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