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

Goes well beyond the annotations: discloses that the operation is additive ('other functions stay'), that Code functions run saved tests first and abort attachment on failure, and that secret header values must never be echoed. These are non-obvious failure and safety behaviours an agent could not infer from readOnly/destructive/idempotent hints.

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 purpose, then constraints, then the confirmation requirement in a tight sequence of short clauses. Dense but every sentence carries information; only the display-field enumeration is slightly procedural.

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 only two fully documented parameters, rich annotations and no output schema, the description covers the remaining gaps: what happens on test failure, that existing attachments persist, and the confirmation/secret-handling protocol. Nothing needed to invoke 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 100% and both parameters document their source (listAgents, agent_functions_list). The description only refers generically to 'the exact function, receptionist', adding no syntax or format detail beyond the schema, so 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?

States a specific verb and resource ('Attach an existing Agent Function to one receptionist') plus the runtime effect ('so it can call it on live calls'). Clearly distinguishes itself from the create_code/create_http siblings because it says 'existing'.

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?

Implies this is the path for functions that already exist (contrasted with the create_* siblings) and gives the confirmation prerequisite before calling. It never explicitly says when to prefer creating a new function instead, so it sits just below the top mark.

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