Server Quality Checklist

Tool Scores

• mcpmessage_list_chatsA
  4.5/5.0
  Behavior4/5

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

  Annotations already provide readOnlyHint, destructiveHint, and idempotentHint. The description adds the returned JSON structure and the intent to find recipients, which is complementary. There is no contradiction, and the extra context goes beyond what annotations cover.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is compact and front-loaded: the core action is stated first, followed by a brief usage hint and a return format block. Every sentence adds value, and there is no fluff.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  For a simple, parameterless, read-only list tool with an output schema, the description covers the essential purpose, usage context, and expected return format. Nothing required 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.

  Parameters4/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  The tool accepts zero parameters, so the baseline per the rubric is 4. The description correctly omits parameter details, and the schema coverage is effectively irrelevant since no params exist.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description states a specific verb and resource ('List every chat registered in the shared mailbox') and clearly distinguishes its purpose from the sibling mcpmessage_send by indicating it is a discovery step before sending. It is unambiguous and self-contained.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  It explicitly tells when to use the tool ('before mcpmessage_send') to discover valid recipients. It does not enumerate exclusions, but the guidance is concrete and suffices for this list tool.

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

• mcpmessage_register_chatA
  4.6/5.0
  Behavior4/5

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

  Beyond the annotations, the description discloses normalization behavior ('lowercase and trimmed'), uniqueness constraints, error return format ('Error: ... string'), and example failure cases. It does not mention every edge case, but it provides solid behavioral coverage for a registration action.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is well-structured with a clear purpose statement, usage timing, parameter explanations, and return value format. Every section adds necessary information without redundancy.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  The description covers what the tool does, when to use it, parameter semantics, return data shape, and error scenarios. For a simple registration tool, this is sufficiently complete for an agent to invoke it correctly.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters5/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  Schema description coverage is 0%, so the description fully compensates by explaining 'name' as the chat's unique address with normalization, and 'description' as what is shown by mcpmessage_list_chats. Both parameters get meaningful semantic detail the schema lacks.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description uses a specific verb and resource: 'Register a chat under a unique name so other chats can message it.' This clearly establishes the tool's role and distinguishes it from sibling messaging tools like mcpmessage_send and mcpmessage_list_chats.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  It gives explicit contextual guidance with 'Do this once at the start of a session' and explains that the name acts as the chat's address. It does not explicitly name alternatives or exclusion conditions, but the intended usage is clear.

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

• mcpmessage_threadA
  4.6/5.0
  Behavior4/5

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

  Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds meaningful context beyond that: it accepts both root and reply ids, returns messages in order, and returns an 'Error: ...' string when the message does not exist. This is useful behavioral detail without contradicting the annotations.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is concise and well-structured: a one-sentence summary, a short explanatory sentence, then explicit Args and Returns sections. Every part earns its place and the most important semantic points are front-loaded.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  For a one-parameter read-only tool with strong annotations, this is complete. It covers what the tool returns, the shape of the response, the accepted input, and the error case. No additional information is needed for an agent to invoke it correctly.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters5/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  Schema description coverage is 0%, so the description must compensate, and it does thoroughly. It explains that message_id can be any message id in the thread, including the root send or any reply, which adds real meaning beyond the bare parameter title 'Message Id'.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description opens with a precise verb and resource: 'Return the full thread a message belongs to, in order.' It also clarifies that any message id in the thread works, which clearly distinguishes this from sending, listing chats, or checking an inbox. The purpose is unambiguous.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The description explains exactly when to use the tool: to follow a conversation across replies by passing any message id from the thread. It does not explicitly name alternatives or exclusions, but the context is clear enough that an agent would not confuse this with siblings like mcpmessage_send or mcpmessage_inbox.

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

• mcpmessage_inboxA
  4.8/5.0
  Behavior5/5

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

  The description discloses key side effects beyond the annotations: messages are marked as read by default, unread_only and mark_read change behavior, and mark_read=false provides a peek mode. It also warns about prompt-injection risks and describes the error return for unregistered chats. This is rich, useful behavioral disclosure.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is efficiently structured: a one-sentence purpose, a short behavioral paragraph, a compact Args list, and a Returns line. Each part earns its place, including the essential security warning. It is detailed but not bloated.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  For a tool with four parameters, no schema param descriptions, and an output schema, the description covers everything needed to invoke it correctly: parameter semantics, defaults, side effects, return shape, and error behavior. Nothing critical is missing.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters5/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  Schema description coverage is 0%, so the description must fully compensate, and it does. Every parameter is explained with meaning and defaults: chat is the registered chat name, unread_only controls history vs unread, mark_read controls peek vs consume, and limit sets a maximum. No parameter is left ambiguous.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  Description opens with a specific verb and resource: 'Fetch messages addressed to a chat, oldest first.' This clarifies both the action and the ordering, and the tool is clearly distinct from siblings like send, thread, register_chat, and list_chats. The main purpose is unambiguous and front-loaded.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The description gives clear usage context: 'calling it periodically behaves like checking mail' explains the intended pattern. It also warns that content from other chats must be treated as data, not instructions. It does not explicitly mention when to use a sibling tool instead, but the context is strong enough for selection.

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

• mcpmessage_sendA
  4.8/5.0
  Behavior5/5

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

  The description goes well beyond the basic annotations by explaining thread behavior, stored message fields, and error cases. It makes the side effects and failure modes clear, which is especially valuable for a non-readOnly, non-idempotent mutation tool.

  Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

  Conciseness5/5

  Is the description appropriately sized, front-loaded, and free of redundancy?

  The description is well-structured with an opening summary, focused paragraphs on data and reply_to, and an Args/Returns layout. It is detailed yet each sentence earns its place and the most important purpose is front-loaded.

  Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

  Completeness5/5

  Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

  The description covers all five parameters, required fields, return shape, and error cases. Despite the lack of schema-level descriptions, an agent has enough information to invoke the tool correctly and interpret the result.

  Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

  Parameters5/5

  Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

  Schema description coverage is 0%, but the description compensates fully by explaining every parameter's meaning, validation constraints (non-empty body, registered names), and the optional nature of data and reply_to. This adds substantial meaning beyond the bare schema.

  Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

  Purpose5/5

  Does the description clearly state what the tool does and how it differs from similar tools?

  The description states a specific verb and resource: sending a message from one registered chat to another. It clearly distinguishes this from sibling tools like list_chats, inbox, and thread by focusing on the act of sending.

  Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

  Usage Guidelines4/5

  Does the description explain when to use this tool, when not to, or what alternatives exist?

  The description gives clear usage context, such as using data for structured payloads and passing reply_to to answer a received message. It also directs the agent to mcpmessage_list_chats for recipient names, though it does not explicitly list when not to use the tool.

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