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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=true): it discloses that the key is stored encrypted, never returned by any tool, and not logged, states the one-key-per-account cardinality, the authorization requirement, and the return shape { set, setAt }. This is exactly the behavioural context annotations cannot express.

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?

Front-loaded with the core statement and the key operational facts packed efficiently. The trailing Portuguese translation sentence is redundant for an English-reading agent, costing a little tightness without harming comprehension.

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 mutation with no output schema, the description covers purpose, prerequisites, permissions, format, storage guarantees, ordering relative to siblings, and the return value. Nothing an agent needs in order to call it correctly 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?

Schema coverage is already 100%, but the description still adds value: the input format (16–128 letters, digits, '-', '_'), its provenance (generated under Settings → API access), and that it is 'pasted in the chat'. That supplements rather than repeats 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?

States a precise verb+resource ('Stores the Bing Webmaster Tools API key of the Organiq account') and immediately distinguishes it from the sibling set_bing_site by noting the key 'serves every property with a Bing site set by set_bing_site'. An agent can tell exactly what this tool does versus its neighbours.

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?

Gives explicit trigger conditions: 'Use it after set_bing_site, or when get_bing_performance / check_connection report the key missing', and names the sibling tools involved. It also specifies the precondition (owner/admin, mcp:write scope) and the failure mode (insufficient_scope).

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