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

Annotations already declare write/idempotent/non-destructive/non-openWorld. The description adds genuinely non-obvious behavior: values are sealed immediately, are never returned by any tool or page, and are read only by the gateway. That write-only secret semantics is exactly the kind of context annotations can't convey, though it omits what happens on failure or whether the replacement is transactional.

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 sentences, zero filler, and the core mutation is front-loaded before the behavioral caveat. Every clause earns its place.

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 and full annotation coverage, the description supplies the missing behavioral picture: irreversible-looking overwrite, secrecy, and value sourcing. It is nearly complete; only error/permission conditions are left unstated.

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 each parameter is documented in the schema, so the baseline is 3. The description reinforces the replace-not-merge semantics of 'headers' and the sourcing of values, but adds no format or structural detail 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?

The description uses a specific verb+resource ('Store the header set ... replacing any stored set') and scopes it to an 'organization-held static_headers scope', which implicitly separates it from the sibling set_gateway_scope_oauth_client. It is clear what the tool does, though it never names the alternative tool 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?

It gives one piece of sourcing guidance ('Ask the person for the values rather than inventing them'), which is useful. However, it does not state when to use this versus set_gateway_scope_oauth_client or disconnect_gateway_scope, nor any explicit prerequisites beyond what the schema's auth_mode constraint carries. Usage is implied rather than stated.

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